io_uring: remove extra argument for overflow flush

Unlike __io_cqring_overflow_flush(), nobody does forced flushing with
io_cqring_overflow_flush(), so removed the argument from it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7594f869ca41b7cfb5a35a3c7c2d402242834e9e.1628536684.git.asml.silence@gmail.com


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