refactor(stm32mp1): reduce MMU memory regions and split XLAT by context

Simplify the BL2 MMU mapping and reduce the memory regions
number. Split the XLAT define between BL2 and BL32 as binaries
do not share the same tables anymore.

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Change-Id: Iaf09e72b4cc29acbe376f6f1cd2a8116c793ba26
1 file changed