io-wq: reduce acct->lock crossing functions lock/unlock

reduce acct->lock lock and unlock in different functions to make the
code clearer.

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220206095241.121485-3-haoxu@linux.alibaba.com


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