vlan: introduce __vlan_find_dev_deep()

Since vlan_group_get_device and vlan_group is not going to be accessible
from device drivers, introduce function which substitutes it.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index cfb0cf2..69391cc 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -120,6 +120,8 @@
 
 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 
+extern struct net_device *__vlan_find_dev_deep(struct net_device *real_dev,
+					       u16 vlan_id);
 extern struct net_device *vlan_dev_real_dev(const struct net_device *dev);
 extern u16 vlan_dev_vlan_id(const struct net_device *dev);
 
@@ -135,6 +137,12 @@
 	       unsigned int vlan_tci);
 
 #else
+static inline struct net_device *
+__vlan_find_dev_deep(struct net_device *real_dev, u16 vlan_id)
+{
+	return NULL;
+}
+
 static inline struct net_device *vlan_dev_real_dev(const struct net_device *dev)
 {
 	BUG();