ipv6/dccp: do not inherit ipv6_mc_list from parent

Like commit 657831ffc38e ("dccp/tcp: do not inherit mc_list from parent")
we should clear ipv6_mc_list etc. for IPv6 sockets too.

Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
static u32 tcp_v6_init_seq(const struct sk_buff *skb)
{
	return secure_tcpv6_seq(ipv6_hdr(skb)->daddr.s6_addr32,
				ipv6_hdr(skb)->saddr.s6_addr32,
				tcp_hdr(skb)->dest,
				tcp_hdr(skb)->source);
}

static u32 tcp_v6_init_seq(const struct sk_buff *skb)
{
	return secure_tcpv6_seq(ipv6_hdr(skb)->daddr.s6_addr32,
				ipv6_hdr(skb)->saddr.s6_addr32,
				tcp_hdr(skb)->dest,
				tcp_hdr(skb)->source);
}
