feat(stm32mp1): add stm32_get_boot_interface function

Add function stm32_get_boot_interface to get the current boot interface
from information saved in the TAMP register.

Change-Id: I23af43c68eeaebe4c45920a57d739117aea3fbb1
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
2 files changed