io_uring/net: clear REQ_F_BL_EMPTY in the multishot retry handler

This flag should not be persistent across retries, so ensure we clear
it before potentially attemting a retry.

Fixes: c3f9109d ("io_uring/kbuf: flag request if buffer pool is empty after buffer pick")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/net.c

@@ -676,6 +676,7 @@ static inline void io_recv_prep_retry(struct io_kiocb *req)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
 
+	req->flags &= ~REQ_F_BL_EMPTY;
 	sr->done_io = 0;
 	sr->len = 0; /* get from the provided buffer */
 	req->buf_index = sr->buf_group;