dm: small cleanup in dm_get_md()

Makes dm_get_md() and dm_get_from_kobject() have similar code.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm.c

@@ -2074,17 +2074,12 @@ struct mapped_device *dm_get_md(dev_t dev)
 	spin_lock(&_minor_lock);
 
 	md = idr_find(&_minor_idr, minor);
-	if (md) {
-		if ((md == MINOR_ALLOCED ||
-		     (MINOR(disk_devt(dm_disk(md))) != minor) ||
-		     dm_deleting_md(md) ||
-		     test_bit(DMF_FREEING, &md->flags))) {
+	if (!md || md == MINOR_ALLOCED || (MINOR(disk_devt(dm_disk(md))) != minor) ||
+	    test_bit(DMF_FREEING, &md->flags) || dm_deleting_md(md)) {
 		md = NULL;
 		goto out;
 	}
 	dm_get(md);
-	}
-
 out:
 	spin_unlock(&_minor_lock);