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>
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index cbfa039..5341ca5 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -691,6 +691,7 @@
 	.statfs		= ovl_statfs,
 	.show_options	= ovl_show_options,
 	.remount_fs	= ovl_remount,
+	.drop_inode	= generic_delete_inode,
 };
 
 enum {