fix(cpus): workaround for Cortex-A520 erratum 2630792

Cortex-A520 erratum is a Cat B erratum that applies
to revisions r0p0 and r0p1 and is still open.
The workaround is to set CPUACTLR_EL1[38] to 1.

SDEN Documentation:
https://developer.arm.com/documentation/SDEN-2444153/latest

Change-Id: Idb6f32f680ee1378a57c2d2f809ea847fffe5910
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index a0f43d5..68d6ef8 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -843,6 +843,10 @@
 # Cortex-A510 cpu and is fixed in r1p3.
 CPU_FLAG_LIST += ERRATA_A510_2684597
 
+# Flag to apply erratum 2630792 workaround during reset. This erratum applies
+# to revisions r0p0, r0p1 of the Cortex-A520 cpu and is still open.
+CPU_FLAG_LIST += ERRATA_A520_2630792
+
 # Flag to apply erratum 2331132 workaround during reset. This erratum applies
 # to revisions r0p0, r0p1 and r0p2. It is still open.
 CPU_FLAG_LIST += ERRATA_V2_2331132