io_uring: Remove unused function

The function are defined in the io_uring.c file, but not called
elsewhere, so delete the unused function.

io_uring/io_uring.c:646:20: warning: unused function '__io_cq_unlock'.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=8660


Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240328022324.78029-1-jiapeng.chong@linux.alibaba.com


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