md: remove unnecessary check on mddev

mddev is never NULL and neither is ->bio_set, so
remove the check.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

drivers/md/md.c

@@ -193,9 +193,6 @@ EXPORT_SYMBOL_GPL(bio_alloc_mddev);
 struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
 			    struct mddev *mddev)
 {
-	if (!mddev || !mddev->bio_set)
-		return bio_clone(bio, gfp_mask);
-
 	return bio_clone_bioset(bio, gfp_mask, mddev->bio_set);
 }
 EXPORT_SYMBOL_GPL(bio_clone_mddev);