fix(cpus): workaround for Cortex-X2 erratum 2778471

Cortex-X2 erratum 2778471 is a Cat B erratum that applies
to revisions r0p1, r1p0, r2p0 and r2p1 and is still open.
The workaround is to set CPUACTLR3_EL1[47] to 1.

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

Change-Id: Ia95f0e276482283bf50e06c58c2bc5faab3f62c6
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
diff --git a/services/std_svc/errata_abi/errata_abi_main.c b/services/std_svc/errata_abi/errata_abi_main.c
index 3e0d139..ecd6b01 100644
--- a/services/std_svc/errata_abi/errata_abi_main.c
+++ b/services/std_svc/errata_abi/errata_abi_main.c
@@ -385,7 +385,8 @@
 			ERRATA_NON_ARM_INTERCONNECT},
 		[10] = {2742423, 0x00, 0x21, ERRATA_X2_2742423},
 		[11] = {2768515, 0x00, 0x21, ERRATA_X2_2768515},
-		[12 ... ERRATA_LIST_END] = UNDEF_ERRATA,
+		[12] = {2778471, 0x00, 0x21, ERRATA_X2_2778471},
+		[13 ... ERRATA_LIST_END] = UNDEF_ERRATA,
 	}
 },
 #endif /* CORTEX_X2_H_INC */