MIPS: Reduce kernel image size for !CONFIG_DEBUG_ZBOOT

!CONFIG_DEBUG_ZBOOT doesn't need puts() and puthex(), remove them and
the corrospindig strings for !CONFIG_DEBUG_ZBOOT, as a result, it saves
about 1280 bytes.

[ralf@linux-mips.org: Resolved reject.]
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/1898/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/boot/compressed/Makefile

@@ -32,9 +32,10 @@ KBUILD_AFLAGS := $(LINUXINCLUDE) $(KBUILD_AFLAGS) -D__ASSEMBLY__ \
 targets := head.o decompress.o string.o dbg.o uart-16550.o uart-alchemy.o
 
 # decompressor objects (linked with vmlinuz)
-vmlinuzobjs-y := $(obj)/head.o $(obj)/decompress.o $(obj)/string.o $(obj)/dbg.o
+vmlinuzobjs-y := $(obj)/head.o $(obj)/decompress.o $(obj)/string.o
 
 ifdef CONFIG_DEBUG_ZBOOT
+vmlinuzobjs-$(CONFIG_DEBUG_ZBOOT)		   += $(obj)/dbg.o
 vmlinuzobjs-$(CONFIG_SYS_SUPPORTS_ZBOOT_UART16550) += $(obj)/uart-16550.o
 vmlinuzobjs-$(CONFIG_MIPS_ALCHEMY)		   += $(obj)/uart-alchemy.o
 endif

arch/mips/boot/compressed/decompress.c

@@ -28,8 +28,13 @@ unsigned long free_mem_end_ptr;
 extern unsigned char __image_begin, __image_end;
 
 /* debug interfaces  */
+#ifdef CONFIG_DEBUG_ZBOOT
 extern void puts(const char *s);
 extern void puthex(unsigned long long val);
+#else
+#define puts(s) do {} while (0)
+#define puthex(val) do {} while (0)
+#endif
 
 void error(char *x)
 {