dm integrity: fix error code in dm_integrity_ctr()

The "r" variable shadows an earlier "r" that has function scope.  It
means that we accidentally return success instead of an error code.
Smatch has a warning for this:

	drivers/md/dm-integrity.c:4503 dm_integrity_ctr()
	warn: missing error code 'r'

Fixes: 7eada90 ("dm: add integrity target")
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

Author: Dan Carpenter

drivers/md/dm-integrity.c

@@ -4494,8 +4494,6 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	}
 
 	if (should_write_sb) {
-		int r;
-
 		init_journal(ic, 0, ic->journal_sections, 0);
 		r = dm_integrity_failed(ic);
 		if (unlikely(r)) {