switch stm32f7 board common to boards/arm/common/stm32.
Move the STM32F7-only board-common features into the shared directory
so they are available to every STM32 family:
- bmi270, cs4344, can_setup, cansock_setup, reset, romfs_initialize and
spitest
- the duplicate stm32_bh1750 is removed (already present in common).
Signed-off-by: raiden00pl <raiden00@railab.me>
