z3fold: remove unused attribute for release_z3fold_page

Since commit dcf5aedb ("z3fold: stricter locking and more careful
reclaim"), release_z3fold_page() is used again.  So we can drop the
unused attribute safely.

Link: https://lkml.kernel.org/r/20210120084008.58432-1-linmiaohe@huawei.com


Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>