[VLAN]: Keep track of number of QoS mappings

Keep track of the number of configured ingress/egress QoS mappings to
avoid iteration while calculating the netlink attribute size.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index aeddb49..b46d422 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -112,7 +112,10 @@
 	/** This will be the mapping that correlates skb->priority to
 	 * 3 bits of VLAN QOS tags...
 	 */
+	unsigned int nr_ingress_mappings;
 	u32 ingress_priority_map[8];
+
+	unsigned int nr_egress_mappings;
 	struct vlan_priority_tci_mapping *egress_priority_map[16]; /* hash table */
 
 	unsigned short vlan_id;        /*  The VLAN Identifier for this interface. */