io_uring: open code io_account_cq_overflow()

io_account_cq_overflow() doesn't help explaining what's going on in
there, and it'll become even smaller with following patches, so open
code it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e4333fa0d371f519e52a71148ebdffed4b8d3aa9.1746788718.git.asml.silence@gmail.com


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