feat(stm32mp1): add FWU with boot from NOR-SPI

Refactor the SDCARD/EMMC FWU, to add the NOR-SPI use case.
SPI-NOR FWU won't use a real partition uuid to find the correct FIP,
but the UUID from metadata will correspond with a hardcoded offset in
the NOR.
While at it change some __unused keywords to __maybe_unused to ease
checkpatch.pl analysis.

Signed-off-by: Frank Bodammer <frank.bodammer@siemens.com>
Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@foss.st.com>
Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I2fe56ba8534a3c5dfaf8aeb16e7b286909883cc2
3 files changed