io_uring: remove unneeded io_send_zc accounting

zc->len and zc->buf are not actually used once you get to the retry
stage. The buffer remains in kmsg->msg.msg_iter, which is setup in
io_send_setup.
Note: it still seems needed in io_send due to io_send_select_buffer
needing it (for the len parameter).

Signed-off-by: Dylan Yudaken <dyudaken@gmail.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: DylanZA

io_uring/net.c

@@ -1493,8 +1493,6 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 			return -EAGAIN;
 
 		if (ret > 0 && io_net_retry(sock, kmsg->msg.msg_flags)) {
-			zc->len -= ret;
-			zc->buf += ret;
 			zc->done_io += ret;
 			return -EAGAIN;
 		}