[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/include/asm-mips/pgalloc.h b/include/asm-mips/pgalloc.h
index af121c6..5685d4f 100644
--- a/include/asm-mips/pgalloc.h
+++ b/include/asm-mips/pgalloc.h
@@ -130,4 +130,6 @@
 
 #define check_pgt_cache()	do { } while (0)
 
+extern void pagetable_init(void);
+
 #endif /* _ASM_PGALLOC_H */