ARM: 7184/1: fix $(CROSS_COMPILE) prefix missing from size invocation

Otherwise, cross compilation may fail with error messages like:

...
size: arch/arm/boot/compressed/../../../../vmlinux: File format is ambiguous
size: Matching formats: elf32-littlearm elf32-littlearm-symbian elf32-littlearm-vxworks
  LD      arch/arm/boot/compressed/vmlinux
  arm-angstrom-linux-uclibcgnueabi-ld:--defsym _kernel_bss_size=: syntax error
Signed-off-by: NJanusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/boot/compressed/Makefile

@@ -126,7 +126,8 @@ ccflags-y := -fpic -fno-builtin -I$(obj)
 asflags-y := -Wa,-march=all
 
 # Supply kernel BSS size to the decompressor via a linker symbol.
-KBSS_SZ = $(shell size $(obj)/../../../../vmlinux | awk 'END{print $$3}')
+KBSS_SZ = $(shell $(CROSS_COMPILE)size $(obj)/../../../../vmlinux | \
+		awk 'END{print $$3}')
 LDFLAGS_vmlinux = --defsym _kernel_bss_size=$(KBSS_SZ)
 # Supply ZRELADDR to the decompressor via a linker symbol.
 ifneq ($(CONFIG_AUTO_ZRELADDR),y)