fix(cpus): workaround for Cortex-X4 erratum 2816013

Cortex-X4 erratum 2816013 is a Cat B erratum that applies
to all revisions <= r0p1 and is fixed in r0p2. This erratum
is only present when memory tagging is enabled.

The workaround is to set CPUACTLR5_EL1[14] to 1.

SDEN documentation:
https://developer.arm.com/documentation/SDEN-2432808/latest

Change-Id: I546044bde6e5eedd0abf61643d25e2dd2036df5c
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index f736b5a..c06bf9e 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -831,6 +831,10 @@
 # to revisions r0p0 and r0p1 of the Cortex-X4 cpu. It is fixed in r0p2.
 CPU_FLAG_LIST += ERRATA_X4_2763018
 
+# Flag to apply erratum 2816013 workaround on reset. This erratum applies
+# to revisions r0p0 and r0p1 of the Cortex-X4 cpu. It is fixed in r0p2.
+CPU_FLAG_LIST += ERRATA_X4_2816013
+
 # Flag to apply erratum 1922240 workaround during reset. This erratum applies
 # to revision r0p0 of the Cortex-A510 cpu and is fixed in r0p1.
 CPU_FLAG_LIST += ERRATA_A510_1922240