md: Reassigned the parameters if read_seqretry returned true in func md_is_badblock.

This bug was introduced by commit(v3.0-rc7-126-g2230dfe).
So fix is suitable for 3.0.y thru 3.6.y.

Cc: stable@vger.kernel.org
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -7936,9 +7936,9 @@ int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
 		   sector_t *first_bad, int *bad_sectors)
 {
 	int hi;
-	int lo = 0;
+	int lo;
 	u64 *p = bb->page;
-	int rv = 0;
+	int rv;
 	sector_t target = s + sectors;
 	unsigned seq;
 
@@ -7953,7 +7953,8 @@ int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
 
 retry:
 	seq = read_seqbegin(&bb->lock);
-
+	lo = 0;
+	rv = 0;
 	hi = bb->count;
 
 	/* Binary search between lo and hi for 'target'