feat(rdn2): add platform id value for rdn2 variant 3

The RD-N2-Cfg3 platform is a variant of the RD-N2 platform with the
significant difference being the number of ITS blocks and the use of a
different part number.

Signed-off-by: Tony K Nadackal <tony.nadackal@arm.com>
Change-Id: Id4c5faeae44f21da79cb59540558192d0b02b124
diff --git a/plat/arm/board/rdn2/include/platform_def.h b/plat/arm/board/rdn2/include/platform_def.h
index 3474016..8e63de5 100644
--- a/plat/arm/board/rdn2/include/platform_def.h
+++ b/plat/arm/board/rdn2/include/platform_def.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2022, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2020-2023, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -92,6 +92,8 @@
 
 #if (CSS_SGI_PLATFORM_VARIANT == 1)
 #define PLAT_ARM_GICR_BASE		UL(0x30100000)
+#elif (CSS_SGI_PLATFORM_VARIANT == 3)
+#define PLAT_ARM_GICR_BASE		UL(0x30300000)
 #else
 #define PLAT_ARM_GICR_BASE		UL(0x301C0000)
 #endif
diff --git a/plat/arm/board/rdn2/platform.mk b/plat/arm/board/rdn2/platform.mk
index 7492fe5..b30e3fc 100644
--- a/plat/arm/board/rdn2/platform.mk
+++ b/plat/arm/board/rdn2/platform.mk
@@ -1,13 +1,13 @@
-# Copyright (c) 2020-2022, Arm Limited and Contributors. All rights reserved.
+# Copyright (c) 2020-2023, Arm Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
-RD_N2_VARIANTS	:= 0 1 2
+RD_N2_VARIANTS	:= 0 1 2 3
 ifneq ($(CSS_SGI_PLATFORM_VARIANT),\
 	$(filter $(CSS_SGI_PLATFORM_VARIANT),$(RD_N2_VARIANTS)))
- $(error "CSS_SGI_PLATFORM_VARIANT for RD-N2 should be 0, 1 or 2, currently set \
-     to ${CSS_SGI_PLATFORM_VARIANT}.")
+ $(error "CSS_SGI_PLATFORM_VARIANT for RD-N2 should be 0, 1, 2 or 3, currently \
+	set to ${CSS_SGI_PLATFORM_VARIANT}.")
 endif
 
 $(eval $(call CREATE_SEQ,SEQ,4))