feat(st): allow AARCH64 compilation for common code

Use read_sctlr_el3() for aarch64 code instead of read_sctlr().

Change-Id: I17b5d1f8cb2918de6ab1d2d56c15cabca0ed43fd
Signed-off-by: Yann Gautier <yann.gautier@st.com>
1 file changed