Btrfs, scrub: uninitialized variable in scrub_extent_for_parity()

The only way that "ret" is set is when we call scrub_pages_for_parity()
so the skip to "if (ret) " test doesn't make sense and causes a static
checker warning.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NChris Mason <clm@fb.com>

fs/btrfs/scrub.c

@@ -2607,9 +2607,9 @@ static int scrub_extent_for_parity(struct scrub_parity *sparity,
 		ret = scrub_pages_for_parity(sparity, logical, l, physical, dev,
 					     flags, gen, mirror_num,
 					     have_csum ? csum : NULL);
-skip:
 		if (ret)
 			return ret;
+skip:
 		len -= l;
 		logical += l;
 		physical += l;