net: Add MDB get device operation

Add MDB net device operation that will be invoked by rtnetlink code in
response to received RTM_GETMDB messages. Subsequent patches will
implement the operation in the bridge and VXLAN drivers.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1609,6 +1609,10 @@ struct net_device_ops {
 	int			(*ndo_mdb_dump)(struct net_device *dev,
 						struct sk_buff *skb,
 						struct netlink_callback *cb);
+	int			(*ndo_mdb_get)(struct net_device *dev,
+					       struct nlattr *tb[], u32 portid,
+					       u32 seq,
+					       struct netlink_ext_ack *extack);
 	int			(*ndo_bridge_setlink)(struct net_device *dev,
 						      struct nlmsghdr *nlh,
 						      u16 flags,