sh: Shut up compiler warnings in __do_page_fault().

GCC doesn't seem to be able to figure this one out for
itself, so just shut it up..

  CC      arch/sh/mm/fault.o
arch/sh/mm/fault.c: In function '__do_page_fault':
arch/sh/mm/fault.c:288: warning: 'ptl' may be used uninitialized in this function

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 9207da6..62d0289 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -285,7 +285,7 @@
 	pte_t *pte;
 	pte_t entry;
 	struct mm_struct *mm = current->mm;
-	spinlock_t *ptl;
+	spinlock_t *ptl = NULL;
 	int ret = 1;
 
 #ifdef CONFIG_SH_KGDB