netfilter: ip6tables: use skb->len for accounting

ipv6_hdr(skb)->payload_len is ZERO and can't be used for accounting, if
the payload is a Jumbo Payload specified in RFC2675.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

net/ipv6/netfilter/ip6_tables.c

@@ -387,9 +387,7 @@ ip6t_do_table(struct sk_buff *skb,
 				goto no_match;
 		}
 
-		ADD_COUNTER(e->counters,
-			    ntohs(ipv6_hdr(skb)->payload_len) +
-			    sizeof(struct ipv6hdr), 1);
+		ADD_COUNTER(e->counters, skb->len, 1);
 
 		t = ip6t_get_target_c(e);
 		IP_NF_ASSERT(t->u.kernel.target);