aufs: for v5.15-rc1, no mand-lock anymore

commit 494b53204c49afc0ef9c29acf17455a4ac857c97 aufs5-standalone upstream.

By the commit,
	f7e33bdb 2021-08-23 fs: remove mandatory file locking support
it was gone.

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>