last_low_overflow_time is not used anymore after commit bf20ab53
("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW").
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20240903135149.271857-2-yukuai1@huaweicloud.comSigned-off-by: Jens Axboe <axboe@kernel.dk>