Neovers N1: added support to update presence of External LLC

CPUECTLR_EL1.EXTLLC bit indicates the presense of internal or external
last level cache(LLC) in the system, the reset value is internal LLC.

To cater for the platforms(like N1SDP) which has external LLC present
introduce a new build option 'NEOVERSE_N1_EXTERNAL_LLC' which can be
enabled by platform port.

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: Ibf475fcd6fd44401897a71600f4eafe989921363
diff --git a/include/lib/cpus/aarch64/neoverse_n1.h b/include/lib/cpus/aarch64/neoverse_n1.h
index fa733ce..b50befa 100644
--- a/include/lib/cpus/aarch64/neoverse_n1.h
+++ b/include/lib/cpus/aarch64/neoverse_n1.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -35,6 +35,7 @@
 
 #define NEOVERSE_N1_WS_THR_L2_MASK	(ULL(3) << 24)
 #define NEOVERSE_N1_CPUECTLR_EL1_MM_TLBPF_DIS_BIT	(ULL(1) << 51)
+#define NEOVERSE_N1_CPUECTLR_EL1_EXTLLC_BIT		(ULL(1) << 0)
 
 /*******************************************************************************
  * CPU Auxiliary Control register specific definitions.