bonding: do vlan cleanup

Now when all devices are cleaned up, bond can be cleaned up as well

- remove bond->vlgrp
- remove bond_vlan_rx_register
- substitute necessary occurences of vlan_group_get_device

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>