fix(cpus): workaround for Cortex-X3 erratum 2742421

Cortex-X3 erratum 2742421 is a Cat B erratum that applies to
all revisions <= r1p1 and is fixed in r1p2. The workaround is to
set CPUACTLR5_EL1[56:55] to 2'b01.

SDEN documentation:
https://developer.arm.com/documentation/2055130/latest

Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
Change-Id: Idadd323e419739fe909b9b68ea2dbe857846666b
diff --git a/services/std_svc/errata_abi/errata_abi_main.c b/services/std_svc/errata_abi/errata_abi_main.c
index a37c374..4060ebb 100644
--- a/services/std_svc/errata_abi/errata_abi_main.c
+++ b/services/std_svc/errata_abi/errata_abi_main.c
@@ -424,7 +424,8 @@
 	.cpu_errata_list = {
 		[0] = {2313909, 0x00, 0x10, ERRATA_X3_2313909},
 		[1] = {2615812, 0x00, 0x11, ERRATA_X3_2615812},
-		[2 ... ERRATA_LIST_END] = UNDEF_ERRATA,
+		[2] = {2742421, 0x00, 0x11, ERRATA_X3_2742421},
+		[3 ... ERRATA_LIST_END] = UNDEF_ERRATA,
 	}
 },
 #endif /* CORTEX_X3_H_INC */