[MIPS] Add external declaration of pagetable_init() to pgalloc.h

This fixes some sparse warnings.

pgtable-32.c:15:6: warning: symbol 'pgd_init' was not declared. Should it be static?
pgtable-32.c:32:13: warning: symbol 'pagetable_init' was not declared. Should it be 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/mm/pgtable-64.c b/arch/mips/mm/pgtable-64.c
index c46eb65..e4b565a 100644
--- a/arch/mips/mm/pgtable-64.c
+++ b/arch/mips/mm/pgtable-64.c
@@ -10,6 +10,7 @@
 #include <linux/mm.h>
 #include <asm/fixmap.h>
 #include <asm/pgtable.h>
+#include <asm/pgalloc.h>
 
 void pgd_init(unsigned long page)
 {