netfilter: ipv6: unnecessary to check whether ip6_route_output() returns NULL

ip6_route_output() never returns NULL, so it is not appropriate to
check if the return value is NULL.
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/ipv6/netfilter/nf_reject_ipv6.c

@@ -158,7 +158,7 @@ void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook)
 	fl6.fl6_dport = otcph->source;
 	security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6));
 	dst = ip6_route_output(net, NULL, &fl6);
-	if (dst == NULL || dst->error) {
+	if (dst->error) {
 		dst_release(dst);
 		return;
 	}