fix(cpus): workaround for Cortex-X2 erratum 3701772

Cortex-X2 erratum 3701772 that applies to r0p0, r1p0, r2p0, r2p1
is still Open.

The workaround is for EL3 software that performs context save/restore
on a change of Security state to use a value of SCR_EL3.NS when
accessing ICH_VMCR_EL2 that reflects the Security state that owns the
data being saved or restored.

SDEN documentation:
https://developer.arm.com/documentation/SDEN-1775100/latest/

Change-Id: I2ffc5e7d7467f1bcff8b895fea52a1daa7d14495
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 747edf4..a879bb0 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -786,6 +786,11 @@
 # to revisions r0p0, r1p0, r2p0, r2p1 of the Cortex-X2 cpu and it is still open.
 CPU_FLAG_LIST += ERRATA_X2_2778471
 
+# Flag to apply erratum 3701772 workaround during context save/restore of
+# ICH_VMCR_EL2 reg. This erratum applies to revisions r0p0, r1p0, r2p0 and r2p1
+# of the Cortex-X2 cpu and is still open.
+CPU_FLAG_LIST += ERRATA_X2_3701772
+
 # Flag to apply erratum 2070301 workaround on reset. This erratum applies
 # to revisions r0p0, r1p0, r1p1 and r1p2 of the Cortex-X3 cpu and is
 # still open.