openvswitch: Only set TUNNEL_VXLAN_OPT if VXLAN-GBP metadata is set

This avoids setting TUNNEL_VXLAN_OPT for VXLAN frames which don't
have any GBP metadata set. It is not invalid to set it but unnecessary.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/openvswitch/vport-vxlan.c b/net/openvswitch/vport-vxlan.c
index ff07d40..3277a75 100644
--- a/net/openvswitch/vport-vxlan.c
+++ b/net/openvswitch/vport-vxlan.c
@@ -76,7 +76,7 @@
 
 	flags = TUNNEL_KEY | (udp_hdr(skb)->check != 0 ? TUNNEL_CSUM : 0);
 	vxlan_port = vxlan_vport(vport);
-	if (vxlan_port->exts & VXLAN_F_GBP)
+	if (vxlan_port->exts & VXLAN_F_GBP && md->gbp)
 		flags |= TUNNEL_VXLAN_OPT;
 
 	/* Save outer tunnel values */