block: fix improper kobject release in blk_integrity_unregister

blk_integrity_unregister should use kobject_put to release the kobject,
otherwise after bi is freed, memory of bi->kobj->name is leaked.
Signed-off-by: NXiaotian Feng <dfeng@redhat.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

block/blk-integrity.c

@@ -379,6 +379,7 @@ void blk_integrity_unregister(struct gendisk *disk)
 
 	kobject_uevent(&bi->kobj, KOBJ_REMOVE);
 	kobject_del(&bi->kobj);
+	kobject_put(&bi->kobj);
 	kmem_cache_free(integrity_cachep, bi);
 	disk->integrity = NULL;
 }