bridge: mdb: fix double add notification

Since the mdb add/del code was introduced there have been 2 br_mdb_notify
calls when doing br_mdb_add() resulting in 2 notifications on each add.

Example:
 Command: bridge mdb add dev br0 port eth1 grp 239.0.0.1 permanent
 Before patch:
 root@debian:~# bridge monitor all
 [MDB]dev br0 port eth1 grp 239.0.0.1 permanent
 [MDB]dev br0 port eth1 grp 239.0.0.1 permanent

 After patch:
 root@debian:~# bridge monitor all
 [MDB]dev br0 port eth1 grp 239.0.0.1 permanent

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Fixes: cfd567543590 ("bridge: add support of adding and deleting mdb entries")
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_mdb.c

@@ -351,7 +351,6 @@ static int br_mdb_add_group(struct net_bridge *br, struct net_bridge_port *port,
 	if (state == MDB_TEMPORARY)
 		mod_timer(&p->timer, now + br->multicast_membership_interval);
 
-	br_mdb_notify(br->dev, port, group, RTM_NEWMDB);
 	return 0;
 }