s2io: do vlan cleanup

- unify vlan and nonvlan rx path
- kill sp->vlgrp and s2io_vlan_rx_register and s2io_vlan_rx_kill_vid
(which does nothing and is never called :))

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