openvswitch: properly refcount vport-vxlan module

After 614732eaa12d, no refcount is maintained for the vport-vxlan module.
This allows the userspace to remove such module while vport-vxlan
devices still exist, which leads to later oops.

v1 -> v2:
 - move vport 'owner' initialization in ovs_vport_ops_register()
   and make such function a macro

Fixes: 614732eaa12d ("openvswitch: Use regular VXLAN net_device device")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
index e194c10a..31cbc8c 100644
--- a/net/openvswitch/vport.c
+++ b/net/openvswitch/vport.c
@@ -71,7 +71,7 @@
 	return &dev_table[hash & (VPORT_HASH_BUCKETS - 1)];
 }
 
-int ovs_vport_ops_register(struct vport_ops *ops)
+int __ovs_vport_ops_register(struct vport_ops *ops)
 {
 	int err = -EEXIST;
 	struct vport_ops *o;
@@ -87,7 +87,7 @@
 	ovs_unlock();
 	return err;
 }
-EXPORT_SYMBOL_GPL(ovs_vport_ops_register);
+EXPORT_SYMBOL_GPL(__ovs_vport_ops_register);
 
 void ovs_vport_ops_unregister(struct vport_ops *ops)
 {