Add "st,package" entry. Possibles values are:
-STM32MP_PKG_AA for LFBGA448 (18*18) package
-STM32MP_PKG_AB for LFBGA354 (16*16) package
-STM32MP_PKG_AC for TFBGA361 (12*12) package
-STM32MP_PKG_AD for TFBGA257 (10*10) package

see Linux commit 966d9b928f626a54a0c27c0fdae1e3dfe9bab416
for v5.2-rc1
Signed-off-by: NPatrick Delaunay <patrick.delaunay@st.com>