vlan: Add extack messages for link create

Add informative messages for error paths related to adding a
VLAN to a device.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/8021q/vlan.h b/net/8021q/vlan.h
index e23aac3..44df1c3 100644
--- a/net/8021q/vlan.h
+++ b/net/8021q/vlan.h
@@ -109,7 +109,8 @@ int vlan_dev_change_flags(const struct net_device *dev, u32 flag, u32 mask);
 void vlan_dev_get_realdev_name(const struct net_device *dev, char *result);
 
 int vlan_check_real_dev(struct net_device *real_dev,
-			__be16 protocol, u16 vlan_id);
+			__be16 protocol, u16 vlan_id,
+			struct netlink_ext_ack *extack);
 void vlan_setup(struct net_device *dev);
 int register_vlan_dev(struct net_device *dev, struct netlink_ext_ack *extack);
 void unregister_vlan_dev(struct net_device *dev, struct list_head *head);