io_uring: move non aligned field to the end

Move not cache aligned fields down in io_ring_ctx, should change
anything, but makes further refactoring easier.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/518e95d7888e9d481b2c5968dcf3f23db9ea47a5.1692916914.git.asml.silence@gmail.com


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