io_uring/net: combine fail handlers

Merge io_send_zc_fail() into io_sendrecv_fail(), saves a few lines of
code and some headache for following patch.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e0eba1d577413aef5602cd45f588b9230207082d.1663668091.git.asml.silence@gmail.com


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