Add SPIv2 driver for STM32U5 using TXDR/RXDR and CFG1/CFG2 registers,
which differ from the classic SPI peripheral on older STM32 families.
Implements Configure() and single-byte Transfer().
Add SPI1 peripheral and pin definitions to arduino-uno-q board.
Exclude stm32u5 from the shared classic SPI build tag.
deadprogram