nvmet-tcp: fix uninitialized variable access

If we end up in nvmet_tcp_try_recv_one with a bogus state
queue receive state we will access result which is uninitialized.

Initialize restult to 0 which will be considered as if no data
was received by the tcp socket.

Fixes: 872d26a3 ("nvmet-tcp: add NVMe over TCP target driver")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/target/tcp.c

@@ -1089,7 +1089,7 @@ static int nvmet_tcp_try_recv_ddgst(struct nvmet_tcp_queue *queue)
 
 static int nvmet_tcp_try_recv_one(struct nvmet_tcp_queue *queue)
 {
-	int result;
+	int result = 0;
 
 	if (unlikely(queue->rcv_state == NVMET_TCP_RECV_ERR))
 		return 0;