[IPV6]: Move nextheader offset to the IP6CB

Move nextheader offset to the IP6CB to make it possible to pass a
packet to ip6_input_finish multiple times and have it skip already
parsed headers. As a nice side effect this gets rid of the manual
hopopts skipping in ip6_input_finish.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 683250a..df07425 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -1029,7 +1029,7 @@
 	return 0;
 }
 
-static int dccp_v6_rcv(struct sk_buff **pskb, unsigned int *nhoffp)
+static int dccp_v6_rcv(struct sk_buff **pskb)
 {
 	const struct dccp_hdr *dh;
 	struct sk_buff *skb = *pskb;