writeback: remove obsolete macro EXPIRE_DIRTY_ATIME

EXPIRE_DIRTY_ATIME is not used anymore. Remove it.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20221210101042.2012931-1-linmiaohe@huawei.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>