dev-arm: Added trusted DRAM to vexpress Realview

Added the 32MB of trusted DRAM to the VExpress_GEM5_Base Realview.
This trusted DRAM is however not protected against unsecure access.

This commit is part of series of commit to enable booting OPTEE on gem5.

Change-Id: Icbbaec8488dd72e1cbe70015a7f7904de35b38bf
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/49989
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/arm/RealView.py

@@ -977,7 +977,9 @@ References:
 
 Memory map:
    0x00000000-0x03ffffff: Boot memory (CS0)
-   0x04000000-0x07ffffff: Reserved
+   0x04000000-0x07ffffff: Trusted Memory/Reserved
+        0x04000000-0x0403FFFF: 256kB Trusted SRAM
+        0x06000000-0x07ffffff: 32MB Trusted DRAM
    0x08000000-0x0bffffff: NOR FLASH0 (CS0 alias)
    0x0c000000-0x0fffffff: NOR FLASH1 (Off-chip, CS4)
    0x10000000-0x13ffffff: gem5-specific peripherals (Off-chip, CS5)
@@ -1094,7 +1096,10 @@ Interrupts:
     # Trusted SRAM
     trusted_sram = SimpleMemory(range=AddrRange(0x04000000, size='256KiB'),
                                 conf_table_reported=False)
-
+    # Trusted DRAM
+    # TODO: preventing access from unsecure world to the trusted RAM
+    trusted_dram=SimpleMemory(range=AddrRange(0x06000000, size='32MB'),
+                        conf_table_reported=False)
     # Non-Trusted SRAM
     non_trusted_sram = MmioSRAM(range=AddrRange(0x2e000000, size=0x8000),
                                 conf_table_reported=False)
@@ -1145,6 +1150,7 @@ Interrupts:
         memories = [
             self.bootmem,
             self.trusted_sram,
+            self.trusted_dram,
             self.non_trusted_sram,
             self.flash0,
         ]