MIPS: Make setup_elfcorehdr and setup_elfcorehdr_size static

This addresses the following sparse warning:

arch/mips/kernel/setup.c:446:33: warning: symbol 'setup_elfcorehdr_size'
was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/kernel/setup.c

@@ -447,7 +447,7 @@ static int __init early_parse_memmap(char *p)
 early_param("memmap", early_parse_memmap);
 
 #ifdef CONFIG_PROC_VMCORE
-unsigned long setup_elfcorehdr, setup_elfcorehdr_size;
+static unsigned long setup_elfcorehdr, setup_elfcorehdr_size;
 static int __init early_parse_elfcorehdr(char *p)
 {
 	struct memblock_region *mem;