staging: vt6656: rxtx.c s_bPacketToWirelessUsb set fallback tx rates

Set the two TX fall back rates in s_bPacketToWirelessUsb and
pass to private area of driver in variables tx_rate_fb0
and tx_rate_fb1 from the wFB_Opt0/wFB_Opt1 array.

Apply these rates were needed in the TX structure and
remove byFBOption settings in s_uGetRTSCTSDuration.

This greatly simplifies s_uGetRTSCTSDuration and
more future flexibility of setting rates from
upper levels of driver.

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