vexpress: Pass LOADADDR to Makefile

Due to upstream commit 938f94c
("ARM: 7656/1: uImage: Error out on build of multiplatform without LOADADDR"),
vexpress BSP need LOADADDR for making uImage, so pass LOADADDR in the Makefile
for vexpress.

Signed-off-by: Yang Shi <yang.shi@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>

arch/arm/boot/Makefile

@@ -68,6 +68,10 @@ $(obj)/zImage:	$(obj)/compressed/vmlinux FORCE
 
 endif
 
+ifeq ($(CONFIG_ARCH_VEXPRESS), y)
+LOADADDR=0x04080000
+endif
+
 ifneq ($(LOADADDR),)
   UIMAGE_LOADADDR=$(LOADADDR)
 else