ARM: 8541/1: decompressor: drop redundant FORCE in Makefile

The object "piggy.$(suffix_y).o" is created from "piggy.$(suffix).S"
by the following pattern rule defined in scripts/Makefile.build:

  $(obj)/%.o: $(src)/%.S FORCE
          $(call if_changed_dep,as_o_S)

FORCE is already added to the prerequisite of the object there.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/boot/compressed/Makefile

@@ -178,7 +178,7 @@ $(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.$(suffix_y).o \
 $(obj)/piggy.$(suffix_y): $(obj)/../Image FORCE
 	$(call if_changed,$(suffix_y))
 
-$(obj)/piggy.$(suffix_y).o:  $(obj)/piggy.$(suffix_y) FORCE
+$(obj)/piggy.$(suffix_y).o:  $(obj)/piggy.$(suffix_y)
 
 CFLAGS_font.o := -Dstatic=