MIPS: Unify the suffix of compressed vmlinux.bin

The compressed vmlinux.bin is only a temp file so it's ok to use the same
suffix .z for them (.gz,.lzo,.lzma...) to remove several lines and simpify
the maintenance (no need to add the "suffix_$(xxx) := suffix" line).

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
To: linux-mips <linux-mips@linux-mips.org>
Cc: Alexander Clouter <alex@digriz.org.uk>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Patchwork: https://patchwork.linux-mips.org/patch/1323/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

---
diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
index edc48ad..3bdbeef 100644
--- a/arch/mips/boot/compressed/Makefile
+++ b/arch/mips/boot/compressed/Makefile
@@ -48,23 +48,19 @@
 $(obj)/vmlinux.bin: $(KBUILD_IMAGE) FORCE
 	$(call if_changed,objcopy)
 
-suffix_$(CONFIG_KERNEL_GZIP)  = gz
-suffix_$(CONFIG_KERNEL_BZIP2) = bz2
-suffix_$(CONFIG_KERNEL_LZMA)  = lzma
-suffix_$(CONFIG_KERNEL_LZO)   = lzo
 tool_$(CONFIG_KERNEL_GZIP)    = gzip
 tool_$(CONFIG_KERNEL_BZIP2)   = bzip2
 tool_$(CONFIG_KERNEL_LZMA)    = lzma
 tool_$(CONFIG_KERNEL_LZO)     = lzo
 
-targets += vmlinux.gz vmlinux.bz2 vmlinux.lzma vmlinux.lzo
-$(obj)/vmlinux.$(suffix_y): $(obj)/vmlinux.bin FORCE
+targets += vmlinux.bin.z
+$(obj)/vmlinux.bin.z: $(obj)/vmlinux.bin FORCE
 	$(call if_changed,$(tool_y))
 
 targets += piggy.o
-OBJCOPYFLAGS_piggy.o := --add-section=.image=$(obj)/vmlinux.$(suffix_y) \
+OBJCOPYFLAGS_piggy.o := --add-section=.image=$(obj)/vmlinux.bin.z \
                         --set-section-flags=.image=contents,alloc,load,readonly,data
-$(obj)/piggy.o: $(obj)/dummy.o $(obj)/vmlinux.$(suffix_y) FORCE
+$(obj)/piggy.o: $(obj)/dummy.o $(obj)/vmlinux.bin.z FORCE
 	$(call if_changed,objcopy)
 
 LDFLAGS_vmlinuz := $(LDFLAGS) -Ttext $(VMLINUZ_LOAD_ADDRESS) -T