ipv6: use lwtunnel_output6() only if flag redirect is set

This function make sense only when LWTUNNEL_STATE_OUTPUT_REDIRECT is set.
The check is already done in IPv4.

CC: Thomas Graf <tgraf@suug.ch>
CC: Roopa Prabhu <roopa@cumulusnetworks.com>
Fixes: 74a0f2fe ("ipv6: rt6_info output redirect to tunnel output")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -1780,7 +1780,8 @@ int ip6_route_add(struct fib6_config *cfg)
 			goto out;
 		lwtunnel_state_get(lwtstate);
 		rt->rt6i_lwtstate = lwtstate;
-		rt->dst.output = lwtunnel_output6;
+		if (lwtunnel_output_redirect(rt->rt6i_lwtstate))
+			rt->dst.output = lwtunnel_output6;
 	}
 
 	ipv6_addr_prefix(&rt->rt6i_dst.addr, &cfg->fc_dst, cfg->fc_dst_len);