fix(cpus): workaround for Neoverse V1 errata 2779461

Neoverse V1 erratum 2779461 is a Cat B erratum that applies to
all revisions <=r1p2 and is still open.

The workaround sets CPUACTLR3_EL1[47] bit to 1. Setting this
bit might have a small impact on power and negligible impact
on performance.

SDEN documentation:https://developer.arm.com/documentation/SDEN1401781/latest

Change-Id: I367cda1779684638063d7292fda20ca6734e6f10
Signed-off-by: Sona Mathew <SonaRebecca.Mathew@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index ae6baa7..4d50c1b 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -526,6 +526,11 @@
 # still open.
 ERRATA_V1_2743093	?=0
 
+# Flag to apply erratum 2779461 workaround during powerdown. This erratum
+# applies to revisions r0p0, r1p0, r1p1 and r1p2  of the Neoverse V1 cpu and is
+# still open.
+ERRATA_V1_2779461       ?=0
+
 # Flag to apply erratum 1987031 workaround during reset. This erratum applies
 # to revisions r0p0, r1p0 and r2p0 of the Cortex-A710 cpu and is still open.
 ERRATA_A710_1987031	?=0
@@ -1194,6 +1199,10 @@
 $(eval $(call assert_boolean,ERRATA_V1_2743093))
 $(eval $(call add_define,ERRATA_V1_2743093))
 
+# Process ERRATA_V1_2779461 flag
+$(eval $(call assert_boolean,ERRATA_V1_2779461))
+$(eval $(call add_define,ERRATA_V1_2779461))
+
 # Process ERRATA_A710_1987031 flag
 $(eval $(call assert_boolean,ERRATA_A710_1987031))
 $(eval $(call add_define,ERRATA_A710_1987031))