[SCSI] target: iblock/pscsi claim checking for NULL instead of IS_ERR

blkdev_get_by_path() returns an ERR_PTR() or error and it doesn't return
a NULL.  It looks like this bug would be easy to trigger by mistake.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/target/target_core_iblock.c

@@ -154,7 +154,7 @@ static struct se_device *iblock_create_virtdevice(
 
 	bd = blkdev_get_by_path(ib_dev->ibd_udev_path,
 				FMODE_WRITE|FMODE_READ|FMODE_EXCL, ib_dev);
-	if (!(bd))
+	if (IS_ERR(bd))
 		goto failed;
 	/*
 	 * Setup the local scope queue_limits from struct request_queue->limits

drivers/target/target_core_pscsi.c

@@ -462,8 +462,8 @@ static struct se_device *pscsi_create_type_disk(
 	 */
 	bd = blkdev_get_by_path(se_dev->se_dev_udev_path,
 				FMODE_WRITE|FMODE_READ|FMODE_EXCL, pdv);
-	if (!(bd)) {
-		printk("pSCSI: blkdev_get_by_path() failed\n");
+	if (IS_ERR(bd)) {
+		printk(KERN_ERR "pSCSI: blkdev_get_by_path() failed\n");
 		scsi_device_put(sd);
 		return NULL;
 	}