board: stm32mp1: adapt MTD partition for BOOT from NOR or NAND

board: stm32mp1: adapt MTD partition for BOOT from NOR or NAND

Dynamically adapt the MTD partitions in NAND and SPI-NAND when boot from
NOR or NAND/SPI-NAND is detected.

This patch avoids to define the save MTD partition name for NOR and NAND
devices and issue with latest kernel: only the needed MTD partitions
are defined.

For boot from NOR
1/ bootloader (TF-A, U-Boot and OP-TE) in NOR
2/ one large UBI partition in NAND

For boot from NAND
1/ bootloader (TF-A, U-Boot and OP-TE) in MTD raw partition
2/ one large UBI partition

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>