netfilter: nf_ct_ipv6: use ipv6_iface_scope_id in conntrack to return scope id

As in (842df073 ipv6: use newly introduced __ipv6_addr_needs_scope_id and
ipv6_iface_scope_id).

Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c

@@ -330,12 +330,8 @@ ipv6_getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 					sizeof(sin6.sin6_addr));
 
 	nf_ct_put(ct);
-
-	if (ipv6_addr_type(&sin6.sin6_addr) & IPV6_ADDR_LINKLOCAL)
-		sin6.sin6_scope_id = sk->sk_bound_dev_if;
-	else
-		sin6.sin6_scope_id = 0;
-
+	sin6.sin6_scope_id = ipv6_iface_scope_id(&sin6.sin6_addr,
+						 sk->sk_bound_dev_if);
 	return copy_to_user(user, &sin6, sizeof(sin6)) ? -EFAULT : 0;
 }