arm: stm32mp: spl: add bsec driver in SPL

Add the bsec driver in SPL, as it is needed by SOC part number detection
to found the supported OPP.

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