net: Add extack to ndo_add_slave

Pass extack to do_set_master and down to ndo_add_slave

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index c2c9867..e7d5fbb 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -867,7 +867,8 @@ static int batadv_softif_init_late(struct net_device *dev)
  * Return: 0 if successful or error otherwise.
  */
 static int batadv_softif_slave_add(struct net_device *dev,
-				   struct net_device *slave_dev)
+				   struct net_device *slave_dev,
+				   struct netlink_ext_ack *extack)
 {
 	struct batadv_hard_iface *hard_iface;
 	struct net *net = dev_net(dev);