feat(st): use dedicated version of DT for SP_MIN

If an STM32MP15 board is compiled for SP_MIN, and a specific DT file
ending with "-sp_min.dts" exist, then this file will be used to generate
BL2 and BL32 DT.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: Ief6fb4fcf302d07f958a0e2764b149759127f21f
2 files changed