io_uring: add more likely/unlikely() annotations

Add two extra unlikely() in io_submit_sqes() and one around
io_req_needs_clean() to help the compiler to avoid extra jumps
in hot paths.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/88e087afe657e7660194353aada9b00f11d480f9.1633373302.git.asml.silence@gmail.com


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