Little fix to cross compiler objcopy.

Signed-off-by: Georg Lukas <georg@boerde.de>

Index: linux-2.6.20/arch/powerpc/boot/Makefile
===================================================================
--- linux-2.6.20.orig/arch/powerpc/boot/Makefile	2007-03-07 19:01:12.000000000 +0100
+++ linux-2.6.20/arch/powerpc/boot/Makefile	2007-03-07 19:01:21.000000000 +0100
@@ -149,10 +149,10 @@
 $(obj)/zImage.initrd.miboot: vmlinux $(wrapperbits)
 	$(call cmd,wrap_initrd,miboot)
 
 $(obj)/zImage.xenon: vmlinux $(wrapperbits)
 	$(call cmd,wrap,chrp)
-	${CROSS}objcopy -O elf32-powerpc vmlinux vmlinux.xenon
+	$(OBJCOPY) -O elf32-powerpc vmlinux vmlinux.xenon
 
 $(obj)/zImage.ps3: vmlinux
 	$(STRIP) -s -R .comment $< -o $@