io_uring: inline io_req_needs_clean()

There is only a single user of io_req_needs_clean() inline it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6111d0221ef4b439cad401e135dd6a5f990a0501.1633373302.git.asml.silence@gmail.com


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