feat(st): add FWU with boot from NAND

Add the NAND use case in FWU boot. Like the NOR, NAND 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 NAND.
Implement the plat_try_next_boot_source to load
backup partition on specific device.

Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@foss.st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@foss.st.com>
Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I1dc544c479743d0ca2aace6e8214813d75637f50
2 files changed