[POWERPC] boot: rebuild when wrapper changes

Since there is magic defined per platform in the wrapper script, the
zImage targets should depend on it.
Signed-off-by: Milton Miller <miltonm@bga.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/boot/Makefile

@@ -101,7 +101,8 @@ extra-y		:= $(obj)/wrapper.a $(obj-plat) $(obj)/empty.o \
 		   $(obj)/zImage.lds $(obj)/zImage.coff.lds
 
 wrapper		:=$(srctree)/$(src)/wrapper
-wrapperbits	:= $(extra-y) $(addprefix $(obj)/,addnote hack-coff mktree)
+wrapperbits	:= $(extra-y) $(addprefix $(obj)/,addnote hack-coff mktree) \
+			$(wrapper)
 
 #############
 # Bits for building various flavours of zImage