arch/arm: stm32: All SoCs have dts for I2C and SPI

All boards based on STM32 should use dts for I2C and SPI.
Move CONFIG flags selection from boards to arch and select them
for all STM32 SoCs.

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>
5 files changed