rtnetlink: fix FDB size computation

Add missing NDA_VLAN attribute's size.

Fixes: 1e53d5bb8878 ("net: Pass VLAN ID to rtnl_fdb_notify.")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -2852,7 +2852,10 @@ nla_put_failure:
 
 static inline size_t rtnl_fdb_nlmsg_size(void)
 {
-	return NLMSG_ALIGN(sizeof(struct ndmsg)) + nla_total_size(ETH_ALEN);
+	return NLMSG_ALIGN(sizeof(struct ndmsg)) +
+	       nla_total_size(ETH_ALEN) +	/* NDA_LLADDR */
+	       nla_total_size(sizeof(u16)) +	/* NDA_VLAN */
+	       0;
 }
 
 static void rtnl_fdb_notify(struct net_device *dev, u8 *addr, u16 vid, int type,