bridge: Update outdated comment on promiscuous mode

Now bridge ports can be non-promiscuous, vlan_vid_add() is no longer an
unnecessary operation.
Signed-off-by: NToshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bridge/br_vlan.c

@@ -55,10 +55,8 @@ static int __vlan_add(struct net_port_vlans *v, u16 vid, u16 flags)
 
 	if (p) {
 		/* Add VLAN to the device filter if it is supported.
-		 * Stricly speaking, this is not necessary now, since
-		 * devices are made promiscuous by the bridge, but if
-		 * that ever changes this code will allow tagged
-		 * traffic to enter the bridge.
+		 * This ensures tagged traffic enters the bridge when
+		 * promiscuous mode is disabled by br_manage_promisc().
 		 */
 		err = vlan_vid_add(dev, br->vlan_proto, vid);
 		if (err)