staging: vt6656: Get wireless stats qual.qual directly from s_uCalculateLinkQual

Calculate the qual from the tx_packets and wstats.discard.retries and
apply to wstats.qual.qual

Discard pDevice->scStatistic.LinkQuality.

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