MIPS: Loongson: Move prom_argc and prom_argv into prom_init_cmdline()

prom_argc and prom_argv are only used by prom_init_cmdline(), move them
into the function.
Signed-off-by: NWu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: yanh@lemote.com
Cc: huhb@lemote.com
Cc: zhangfx@lemote.com
Patchwork: http://patchwork.linux-mips.org/patch/825/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/loongson/common/cmdline.c

@@ -21,12 +21,11 @@
 
 #include <loongson.h>
 
-int prom_argc;
-/* pmon passes arguments in 32bit pointers */
-int *_prom_argv;
-
 void __init prom_init_cmdline(void)
 {
+	int prom_argc;
+	/* pmon passes arguments in 32bit pointers */
+	int *_prom_argv;
 	int i;
 	long l;