Update submodule nuttx to latest Fri Sep 18 00:40:08 UTC 2020

    - nuttx in PX4/Firmware (1a2f741): PX4/NuttX@1c488eb
    - nuttx current upstream: PX4/NuttX@ec20f2e
    - Changes: PX4/NuttX@1c488eb...ec20f2e

    ec20f2e6c5 2020-09-07 David Sidrane - [BACKPORT] stm32h7:i2c driver fixed interrupt storm
863ed53e3f 2020-06-15 David Sidrane - [BACKPORT] kinetis:Ethernet fixed & better interrupt management
925b7b513b 2020-08-23 Martina Rivizzigno - [BACKPORT] stm32f7 can: fix support for RTR
786378928e 2020-08-25 David Sidrane - [BACKPORT] nuttx:board.h add  extern C under cpp
a96d05c286 2020-08-10 David Sidrane - [BACKPORT] stm32f7:serial TXDMA ISR was looping on TX Empty
2a33d2b6dc 2020-08-04 David Sidrane - [BACKPORT] stm32l4 serial:Add SINGLEWIRE PUSHPULL option
c3f62e1a04 2020-08-04 David Sidrane - [BACKPORT] stm32h7 serial:Add SINGLEWIRE PUSHPULL option
6af3d10af8 2020-08-04 David Sidrane - [BACKPORT] stm32f0l0g0 serial:Add SINGLEWIRE PUSHPULL option
3d49018fd7 2020-08-04 David Sidrane - [BACKPORT] stm32f7 serial:Add SINGLEWIRE PUSHPULL option
a7ac577f87 2020-08-04 David Sidrane - [BACKPORT] stm32 serial:Add SINGLEWIRE PUSHPULL option
870dd3de9d 2020-08-04 David Sidrane - [BACKPORT] tioctl:Define SINGLEWIRE PUSHPULL option
dc10293feb 2020-05-25 Claudio Micheli - [BACKPORT] stm32l4: extend CAN ioctrl with NART/ABOM. Add RTR to CAN header
5735f765e2 2020-05-25 Claudio Micheli - [BACKPORT] stm32: extend CAN ioctrl with NART/ABOM. Add RTR to CAN header
4dc9ae05f5 2020-05-25 Claudio Micheli - [BACKPORT] stm32f7: Add the option to include RTR in CAN header
bdd9e786e1 2020-04-21 Beat Küng - [BACKPORT] stm32f7: add CANIOC_SET_NART and CANIOC_SET_ABOM ioctl's to can driver
61742342ec 2020-07-09 Beat Küng - [BACKPORT] gpio: extend gpio_pintype_e for pulldown/up and opendrain
f5925e194e 2020-06-02 David Sidrane - [BACKPORT] stm32h7:stm32_sdmmc
81d5b634cb 2020-05-27 David Sidrane - [BACKPORT] stm32h7:spi + Restores internal DMA buffer broken in 574b25
7d1882e545 2020-05-27 David Sidrane - [BACKPORT] stm32h7:dma
6690e92a69 2020-05-22 David Sidrane - [BACKPORT] stm32h7:ethernet driver changes
5c4d052d46 2020-05-23 JacobCrabill - [BACKPORT] stm32h7:stm32h7x3xx_rcc Select FDCAN clock source
c9c65c20c9 2020-05-19 David Sidrane - [BACKPORT] stm32h7:stm32h7x3xx_rcc SDMMC2EN is in RCC_AHB2ENR
576b95b644 2020-05-19 David Sidrane - [BACKPORT] stm32h7:ethernet Use proper Clock limits for H7
7c3bd96cdc 2020-05-19 David Sidrane - [BACKPORT] stm32h7:stm32h7x3xx_pinmap Fix missing |
ad035e1544 2020-05-19 David Sidrane - [BACKPORT] stm32h7:stm32h7x3xx_irq STM32_IRQ_SDMMC->STM32_IRQ_SDMMC2
3607a91a1f 2020-05-22 David Sidrane - [BACKPORT] stm32h7:ethernet Use UUID for MAC
66b4f2c4f2 2020-04-21 Peter van der Perk - [Backport] Added S32K1XX progmem driver to use the FlexNVM memory
1b3fc1c668 2020-04-10 Peter van der Perk - Added net_trylock so we can call can_input while being in a interrupt handler
7fffab1610 2020-03-13 David Sidrane - [BACKPORT] Revert "arch/arm/src/stm32f7/stm32_flash.c: Add flash block mapping support for progmem."
ec417d7466 2020-04-06 Peter van der Perk - [Backport] FMUK66 SocketCAN driver & Configurable Bitrate support
a3132cf3b7 2020-03-30 Peter van der Perk - [Backport] SocketCAN support
09f0aee352 2020-04-02 David Sidrane - [BACKPORT] stm32h7:Fix DMA Overrun error
e3c542bbec 2020-03-17 David Sidrane - [BACKPORT] stm32h7:spi Add buffers for DMA
b902d4ca3d 2020-03-23 Peter van der Perk - [BACKPORT] Added S32K1XX FlexTimer register definitions
9d00617188 2020-03-13 David Sidrane - [BACKPORT] stm32f7:spi Add buffers for DMA
f90386f3f9 2020-03-15 Daniel Agar - [BACKPORT] stm32:spi Add buffers for DMA
befe53e7f1 2020-03-12 Jari van Ewijk - [BACKPORT] NXP RDDRONE-UAVCAN boards (S32K1XX) - Clean up clock config (#557)
09a23ebf7f 2020-03-12 Jari van Ewijk - [BACKPORT] NXP S32K1XX EVB boards - clock config cleanup (#556)
6c95d5fc33 2020-03-12 Jari van Ewijk - [BACKPORT] NXP S32K1XX peripheral clock fixes (#555)
db7fb6b6c0 2020-03-05 Jari van Ewijk - [BACKPORT] S32K1xx boards - Remove unused files (should have been renamed)
bf646dcf46 2020-03-03 Daniel Agar - [BACKPORT] stm32h7: spi_exchange (no dma) available with CONFIG_STM32H7_SPI_DMATHRESHOLD
f2a7ef0ade 2020-03-03 Daniel Agar - [BACKPORT] stm32f7: spi_exchange (no dma) available with CONFIG_STM32F7_SPI_DMATHRESHOLD
7ffc59ba3d 2020-03-03 Daniel Agar - [BACKPORT] stm32: spi_exchange (no dma) available with CONFIG_STM32_SPI_DMATHRESHOLD
d1c8fdb5fb 2020-03-02 Daniel Agar - [BACKPORT] arm/stm32h7 add STM32H7_SPI_DMATHRESHOLD
fa8d636118 2020-03-02 Daniel Agar - [BACKPORT] stm32f76xx77xx_dma.h fix DMAMAP_SPI2_RX_2/DMAMAP_SPI2_TX_2
762d80b217 2020-03-02 Daniel Agar - [BACKPORT] arm/stm32f7 add STM32F7_SPI_DMATHRESHOLD
4f4bbbbf1c 2020-03-02 Daniel Agar - [BACKPORT] arm/stm32 add STM32_SPI_DMATHRESHOLD
d509b1edd7 2020-03-01 David Sidrane - [BACKPORT] imxrt: Adds the ability to run from OCRAM (#407)
f6df3a2704 2020-02-29 David Sidrane - [BACKPORT] Add USB Device support for i.MX RT  (#408)
fdf1837077 2020-02-07 Peter van der Perk - [BACKPORT] S32K add support for Nxp drone boards (#224)
f479b26c98 2020-02-07 Peter van der Perk - [BACKPORT] imxrt added missing i2c prescale mask
26dd187034 2020-02-07 Peter van der Perk - [BACKPORT] Kinetis renamed TJA1100 to TJA110X registers
7b36108b54 2020-01-29 David Sidrane - [BACKPORT] imxrt - interrupt serial storm, add DTCM and set up I and D cache  (#175)
0ab870066c 2019-12-13 David Sidrane - [BACKPORT] imxrt106x:pinout add ALT 8 GPIO_GPT2_COMPARE3 & fix GPIO_GPT1_CAPTURE[1|2]
db0e1f7631 2019-12-12 David Sidrane - [BACKPORT] imxrt:lpi2c Fix interrupt storm on failed write.
a30b921af8 2019-12-12 David Sidrane - [BACKPORT] imxrt:lpi2c ensure that on an error status reflects it.
33221379d2 2019-12-12 David Sidrane - [BACKPORT] imxrt:lpi2c imxrt_lpi2c_reset uses GPIO with SION
a5df7d2b8b 2019-12-12 David Sidrane - [BACKPORT] imxrt:gpio Support readback on OUT GPIO
791511ebc9 2019-12-12 David Sidrane - [BACKPORT] imxrt1020-evk: Enable the GPIO based CD.
f2c8fe5e49 2019-12-12 David Sidrane - [BACKPORT] imxrt: Allow clock setting for SPI and I2C from board.h.
46abc7c3c1 2019-12-12 David Sidrane - [BACKPORT] imxrt:lpspi: Fixed race on register setting.
2a9fe676f8 2019-12-12 David Sidrane - [BACKPORT] imxrt:lpspi:  Remove hack setting LPSPI1 daisy irrespective of pin config.
10a7aa88a2 2019-12-12 David Sidrane - [BACKPORT] imxrt:lpi2c.c:Added configurations to fine tune LPI2C Timeouts.
c6ba2c13c7 2019-12-24 David Sidrane - [BACKPORT] STM32F7 and STM32H7 SDMMC internal pull up usage fixed
a14d2cec3b 2019-12-22 David Sidrane - [REJECTED] Add check_format tooling
30e1808bc3 2019-12-22 David Sidrane - [REJECTED] nxstyle - output compiler like error format
9331fda0d7 2019-12-10 David Sidrane - [BACKPORT] IMXRT106x USDHC: Support regular GPIO for CD and inversion.
91c80c708b 2019-12-05 David Sidrane - [BACKPORT] imxrt106x:pinout add ALT 8 GPIO_GPT1_CAPTURE[1|2]
32f758f0e9 2019-12-03 David Sidrane - [BACKPORT] stm32f7:Add Serial Tx DMA
398a59aaa4 2019-11-29 David Sidrane - [BACKPORT] stm32f7:ethernet: Add some delays so that ifup() does not hog the CPU.
2d7920055f 2019-11-28 Beat Küng - [BACKPORT] fix stm32h7x3xx_dmamux.h: add missing underscore to defines