ovl: use generic_delete_inode

No point in keeping overlay inodes around since they will never be reused.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/super.c

@@ -691,6 +691,7 @@ static const struct super_operations ovl_super_operations = {
 	.statfs		= ovl_statfs,
 	.show_options	= ovl_show_options,
 	.remount_fs	= ovl_remount,
+	.drop_inode	= generic_delete_inode,
 };
 
 enum {