staging: vt6656: Remove STAvUpdateTDStatCounter and apply directly to stats

Apply directly to net_device_stats and wireless stats.

tx_bytes are relayed from s_vSaveTxPktInfo via scStatistic,
so collect them there.

All other statistics in STAvUpdateTDStatCounter are dead code
and don't reach user.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>