plat/arm: allow boards to specify second DRAM Base address

The base address for second DRAM varies across different platforms.
So allow platforms to define second DRAM by moving Juno/SGM-775 specific
definition of second DRAM base address to Juno/SGM-775 board definition
respectively, SGI/RD specific definition of DRAM 2 base address to SGI
board definition.

Change-Id: I0ecd3a2bd600b6c7019c7f06f8c452952bd07cae
Signed-off-by: Suyash Pathak <suyash.pathak@arm.com>
diff --git a/plat/arm/board/sgm775/include/platform_def.h b/plat/arm/board/sgm775/include/platform_def.h
index d165ff9..e83cd57 100644
--- a/plat/arm/board/sgm775/include/platform_def.h
+++ b/plat/arm/board/sgm775/include/platform_def.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -12,6 +12,9 @@
 #define PLAT_MAX_CPUS_PER_CLUSTER	U(8)
 #define PLAT_MAX_PE_PER_CPU		U(1)
 
+#define PLAT_ARM_DRAM2_BASE		ULL(0x880000000)
+#define PLAT_ARM_DRAM2_SIZE		ULL(0x180000000)
+
 /*
  * Physical and virtual address space limits for MMU in AARCH64 & AARCH32 modes
  */