There is no hardware limitation for custom boards based on STM32 to uses
SPI bus with signals coming from different PORT and alternate functions.
This patch allow alternate's function definition per pin basis, thus enable
the support of SPI bus signals routed on differents PORT.
Signed-off-by: Yannick Gicquel <ygicquel@gmail.com>
Peripheral configured:
- 5 UARTs for stdio via STLink, Arduino connector, PMOD connector,
STMOD+ connector and ESP-01 connector
- 1 I2C available on Arduino connector and STMOD+ connector
- 2 SPIs available on Arduino connector and PMOD connector
