boards: arm: fk7b0m1_vbt6: add support to external NOR Flash

[CharlesDias]

Updates the DTS file by adding support for Quad SPI and SPI NOR Flash.

This update has been validated via samples/drivers/spi_flash and samples/drivers/flash_shell/.

*** Booting Zephyr OS build zephyr-v3.5.0-4931-ga37bd8e7ba34 ***

spi-nor-flash@0 SPI flash testing
==========================

Perform test on single sector
Test 1: Flash erase
Flash erase succeeded!

Test 2: Flash write
Attempting to write 4 bytes
Data read matches data written. Good!!

Perform test on multiple consequtive sectors
Test 1: Flash erase
Flash erase succeeded!

Test 2: Flash write
Attempting to write 4 bytes at offset 0xff000
Data read matches data written. Good!!
Attempting to write 4 bytes at offset 0x100000
Data read matches data written. Good!!

Flash shell sample[00:00:00.100,000] <inf> flash_stm32_ospi: OSPI flash config is SPI|DUAL|QUAD / STR
[00:00:00.100,000] <inf> flash_stm32_ospi: Read SFDP from octoFlash
[00:00:00.100,000] <inf> flash_stm32_ospi: Read SFDP from octoFlash
*** Booting Zephyr OS build zephyr-v3.5.0-4932-gb3541b2e175e ***
uart:~$ flash page_info qspi-nor-flash@0 0
Page for address 0x0:
start offset: 0x0
size: 4096
index: 0
uart:~$ flash erase qspi-nor-flash@0 0x1000
Erase success.
[00:00:57.477,000] <inf> flash_stm32_ospi: Sector/Block Erase
[00:00:57.477,000] <inf> flash_stm32_ospi: Sector/Block Erase addr 0x1000, asize 0x2000 amode0
uart:~$ flash write qspi-nor-flash@0 0x1000 0x12345678 0x9abcdef0
Write OK.
Verified.
uart:~$ flash read qspi-nor-flash@0 0x1000 0x10
00001000: 78 56 34 12 f0 de bc 9a  ff ff ff ff ff ff ff ff |xV4..... ........|

uart:~$ flash page_info spi-nor-flash@0 0
Page for address 0x0:
start offset: 0x0
size: 65536
index: 0
uart:~$ flash erase spi-nor-flash@0 0x1000
Erase success.
uart:~$ flash write spi-nor-flash@0 0x1000 0x12345678 0x9abcdef0
Write OK.
Verified.
uart:~$ flash read spi-nor-flash@0 0x1000 0x10
00001000: 78 56 34 12 f0 de bc 9a  ff ff ff ff ff ff ff ff |xV4..... ........|

uart:~$ 

[CharlesDias]

Dear @kartben,

Could you help me with this PR? Thanks!

[CharlesDias]

Solved conflicts.

[benediktibk]

Looks like nothing covers boards/fanke in the maintainers file. As this board has a STM32 on it I was so free to add the ST people.