io_uring: pass correct parameters to io_req_set_res

The two parameters of 'res' and 'cflags' are swapped, so fix it.
Without this fix, 'ublk del' hangs forever.

Cc: Pavel Begunkov <asml.silence@gmail.com>
Fixes: de23077e

 ("io_uring: set completion results upfront")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220803120757.1668278-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>