openvswitch: Use correct config guard.

This bug was introduced by commit aa310701
(openvswitch: Add gre tunnel support.)
Signed-off-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/openvswitch/vport-gre.c

@@ -16,7 +16,7 @@
  * 02110-1301, USA
  */
 
-#ifdef CONFIG_NET_IPGRE_DEMUX
+#if IS_ENABLED(CONFIG_NET_IPGRE_DEMUX)
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/if.h>

net/openvswitch/vport.c

@@ -39,7 +39,7 @@ static const struct vport_ops *vport_ops_list[] = {
 	&ovs_netdev_vport_ops,
 	&ovs_internal_vport_ops,
 
-#ifdef CONFIG_NET_IPGRE_DEMUX
+#if IS_ENABLED(CONFIG_NET_IPGRE_DEMUX)
 	&ovs_gre_vport_ops,
 #endif
 };