[MIPS] Make kernel_thread_helper() static

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 9704c21..a669089 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -213,7 +213,7 @@
 /*
  * Create a kernel thread
  */
-ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
+static ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
 {
 	do_exit(fn(arg));
 }