ip6_gre: Set inner protocol correctly in __gre6_xmit

Need to use adjusted protocol value for setting inner protocol.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_gre.c

@@ -519,7 +519,7 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
 	gre_build_header(skb, tunnel->tun_hlen, tunnel->parms.o_flags,
 			 protocol, tunnel->parms.o_key, htonl(tunnel->o_seqno));
 
-	skb_set_inner_protocol(skb, proto);
+	skb_set_inner_protocol(skb, protocol);
 
 	return ip6_tnl_xmit(skb, dev, dsfield, fl6, encap_limit, pmtu,
 			    NEXTHDR_GRE);