blk-integrity: checking for NULL instead of IS_ERR

We recently changed bio_integrity_alloc() to return ERR_PTRs instead of
NULL but these calls were missed.

Fixes: 06c1e390 ('blk-integrity: empty implementation when disabled')
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

block/bio-integrity.c

@@ -298,10 +298,10 @@ int bio_integrity_prep(struct bio *bio)
 
 	/* Allocate bio integrity payload and integrity vectors */
 	bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
-	if (unlikely(bip == NULL)) {
+	if (IS_ERR(bip)) {
 		printk(KERN_ERR "could not allocate data integrity bioset\n");
 		kfree(buf);
-		return -EIO;
+		return PTR_ERR(bip);
 	}
 
 	bip->bip_flags |= BIP_BLOCK_INTEGRITY;
@@ -465,9 +465,8 @@ int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 	BUG_ON(bip_src == NULL);
 
 	bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);
-
-	if (bip == NULL)
-		return -EIO;
+	if (IS_ERR(bip))
+		return PTR_ERR(bip);
 
 	memcpy(bip->bip_vec, bip_src->bip_vec,
 	       bip_src->bip_vcnt * sizeof(struct bio_vec));