[NETFILTER]: nf_nat_proto_gre: add missing module reference

Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/netfilter/nf_nat_proto_gre.c

@@ -138,6 +138,7 @@ gre_manip_pkt(struct sk_buff *skb, unsigned int iphdroff,
 static struct nf_nat_protocol gre __read_mostly = {
 	.name			= "GRE",
 	.protonum		= IPPROTO_GRE,
+	.me			= THIS_MODULE,
 	.manip_pkt		= gre_manip_pkt,
 	.in_range		= gre_in_range,
 	.unique_tuple		= gre_unique_tuple,