move the call of __d_drop(anon) into __d_materialise_unique(dentry, anon)

commit 6f18493e541c690169c3b1479d47d95f624161cf upstream.

and lock the right list there

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>