openvswitch: introduce rtnl ops stub

This stub now allows userspace to see IFLA_INFO_KIND for ovs master and
IFLA_INFO_SLAVE_KIND for slave.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 0d407bc..fe95b6c 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -2054,10 +2054,14 @@
 
 	pr_info("Open vSwitch switching datapath\n");
 
-	err = ovs_flow_init();
+	err = ovs_internal_dev_rtnl_link_register();
 	if (err)
 		goto error;
 
+	err = ovs_flow_init();
+	if (err)
+		goto error_unreg_rtnl_link;
+
 	err = ovs_vport_init();
 	if (err)
 		goto error_flow_exit;
@@ -2084,6 +2088,8 @@
 	ovs_vport_exit();
 error_flow_exit:
 	ovs_flow_exit();
+error_unreg_rtnl_link:
+	ovs_internal_dev_rtnl_link_unregister();
 error:
 	return err;
 }
@@ -2096,6 +2102,7 @@
 	rcu_barrier();
 	ovs_vport_exit();
 	ovs_flow_exit();
+	ovs_internal_dev_rtnl_link_unregister();
 }
 
 module_init(dp_init);