feat(fvp): set defaults for build commandline

When using ARM_LINUX_KERNEL_AS_BL33, set defaults for the below for
increased build time efficiency:

PRELOADED_BL33_BASE=0x80080000
This address supports older kernels before v5.7

ARM_PRELOADED_DTB_BASE=0x87F00000 (only in RESET_TO_BL31)
1MiB before the address 0x88000000 in FVP. 1MiB seems enough for the
device tree blob (DTB).

Change-Id: I0396b597485e163b43f7c6677c04fcc08db55aa8
Signed-off-by: Salman Nabi <salman.nabi@arm.com>
diff --git a/plat/arm/board/fvp/platform.mk b/plat/arm/board/fvp/platform.mk
index 5472a32..7bd2a1d 100644
--- a/plat/arm/board/fvp/platform.mk
+++ b/plat/arm/board/fvp/platform.mk
@@ -372,6 +372,15 @@
 # Set default initrd base 128MiB offset of the default kernel address in FVP
 INITRD_BASE		?=	0x90000000
 
+# Kernel base address supports Linux kernels before v5.7
+# DTB base 1MiB before normal base kernel address in FVP (0x88000000)
+ifeq (${ARM_LINUX_KERNEL_AS_BL33},1)
+    PRELOADED_BL33_BASE ?= 0x80080000
+    ifeq (${RESET_TO_BL31},1)
+        ARM_PRELOADED_DTB_BASE ?= 0x87F00000
+    endif
+endif
+
 ifeq (${TRANSFER_LIST}, 0)
 FDT_SOURCES		+=	$(addprefix plat/arm/board/fvp/fdts/,	\
 					${PLAT}_fw_config.dts		\