io_uring: switch non-defer task_work to io_wq_work_list

io_uring: switch non-defer task_work to io_wq_work_list

Switch the normal task_work to io_wq_work_list as well, to both unify
with defer task_work, but also to avoid needing to reverse the ordering
of the list when running it.

Note that this still keeps the manual retry list for SQPOLL task_work.
That could go away as well, as now the task_work list is fully ordered
and SQPOLL could just leave entries on there when it chops up the
running of the list.

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