8139cp: convert to new VLAN model.

The registers and descriptors bits are identical to the pre-8168
8169 chipsets : {RxDesc / TxDesc}.opts2 can only contain VLAN information.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Reviewed-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>