Enable DMA on AT32F435 SPI

[SteveCEvans]

This PR enables SPI DMA for AT32F435 processors and adds definitions to the AT32F435 target to support use of a gyro connected to the J7 connector of the AT-START-F435 eval card. Note that the AT-START-F435 specifics should be removed from the AT32F435 target definition, but this is just a convenience for now.

The gyro used to test this was a widely available BMI160 evaluation card. This source is just given as an example.

Unfortunately the silk screen on the eval board (and all it's clones that I could find) was wrong.

To save anybody else struggling with this, with reference to the data sheet the wiring for SPI is shown as:

The eval card is silkscreened as shown below:

The required connections are:

AT-START-F435 J7	Eval card	Expected
5V	VIN
GND	GND
SCLK	SCL	SCX
MOSI	SDA	SDX
MISO	SA0
NSS	CS
PB11	INT 1

The detection of both the interrupt and DMA is confirmed by

# status
MCU AT32F435 Clock=288MHz
Stack size: 2048, Stack address: 0x2002fff0
Configuration: CONFIGURED, size: 3114, max available: 16384
Devices detected: SPI:1
Gyros detected: gyro 1 locked dma
GYRO=BMI160, ACC=BMI160
System Uptime: 84 seconds, Current Time: 2023-02-07T22:41:05.662+00:00
CPU:4%, cycle time: 317, GYRO rate: 3154, RX rate: 15, System rate: 9
Voltage: 0 * 0.01V (0S battery - NOT PRESENT)
I2C Errors: 0
Arming disable flags: RXLOSS ANGLE CLI MSP MOTOR_PROTO

# dma show

Currently active DMA:
--------------------
DMA1 Channel 1: SPI_MOSI 2
DMA1 Channel 2: SPI_MISO 2
DMA1 Channel 3: FREE
DMA1 Channel 4: FREE
DMA1 Channel 5: FREE
DMA1 Channel 6: FREE
DMA1 Channel 7: FREE
DMA2 Channel 1: FREE
DMA2 Channel 2: FREE
DMA2 Channel 3: FREE
DMA2 Channel 4: FREE
DMA2 Channel 5: FREE
DMA2 Channel 6: FREE
DMA2 Channel 7: FREE

The traces below show the SPI transfer reading the gyro/accel date.

[github-actions]

Do you want to test this code? Here you have an automated build:
Assets
WARNING: It may be unstable. Use only for testing! See: https://www.youtube.com/watch?v=I1uN9CN30gw for instructions for unified targets!

[blckmn]

AUTOMERGE: (FAIL)

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