feat(stm32mp1): allow to override MTD base offset

Add an external parameter STM32MP_FORCE_MTD_START_OFFSET that allows to
override the default FIP offset used to read the first programmed image.
It can be used for NOR, RAW_NAND or SPI_NAND boot device.

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Change-Id: Ibe664aae0e5ee90dd6629e544c9e034d751fffed
2 files changed