ipv6: mcast: remove dead code

Since commit 41033f02 ("snmp: Remove duplicate OUTMCAST stat
increment") one line of code became unneeded.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/mcast.c

@@ -1655,8 +1655,6 @@ static void mld_sendpack(struct sk_buff *skb)
 	if (err)
 		goto err_out;
 
-	payload_len = skb->len;
-
 	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
 		      net, net->ipv6.igmp_sk, skb, NULL, skb->dev,
 		      dst_output);