io_uring: remove unused wq_list_merge

There are no users of wq_list_merge, kill it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5f9ad0301949213230ad9000a8359d591aae615a.1677002255.git.asml.silence@gmail.com


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