fix(cpus): workaround for Cortex-A78 erratum 2779479

Cortex-A78 erratum 2779479 is a Cat B erratum that applies to
all revisions <= r1p2 and is still open.

The workaround is to set the 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/SDEN1401784/latest

Change-Id: I3779fd1eff3017c5961ffa101b357918070b3b36
Signed-off-by: Sona Mathew <SonaRebecca.Mathew@arm.com>
diff --git a/include/lib/cpus/aarch64/cortex_a78.h b/include/lib/cpus/aarch64/cortex_a78.h
index 31da99e..fb325b6 100644
--- a/include/lib/cpus/aarch64/cortex_a78.h
+++ b/include/lib/cpus/aarch64/cortex_a78.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2022, ARM Limited. All rights reserved.
+ * Copyright (c) 2019-2023, ARM Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -40,6 +40,8 @@
 #define CORTEX_A78_ACTLR2_EL1_BIT_2			(ULL(1) << 2)
 #define CORTEX_A78_ACTLR2_EL1_BIT_40			(ULL(1) << 40)
 
+#define CORTEX_A78_ACTLR3_EL1				S3_0_C15_C1_2
+
 /*******************************************************************************
  * CPU Activity Monitor Unit register specific definitions.
  ******************************************************************************/