tipc: fix a double kfree_skb()

tipc_udp_xmit() drops the packet on error, there is no
need to drop it again.

Fixes: ef20cd4d ("tipc: introduce UDP replicast")
Reported-and-tested-by: syzbot+eae585ba2cc2752d3704@syzkaller.appspotmail.com
Cc: Ying Xue <ying.xue@windriver.com>
Cc: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/tipc/udp_media.c

@@ -245,10 +245,8 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 		}
 
 		err = tipc_udp_xmit(net, _skb, ub, src, &rcast->addr);
-		if (err) {
-			kfree_skb(_skb);
+		if (err)
 			goto out;
-		}
 	}
 	err = 0;
 out: