staging: vt6656: rxtx.c merge pvRTS and pvCTS/pCTS void pointers

As result of patch
rxtx.c s_vGenerateTxParameter create argument bool need rts

RTS and CTS void pointers can be merged.

Create new pointer rts_cts so that unions in s_vFillCTSHead/s_vFillRTSHead
can be joined.

If rts_cts is NULL neither exist.
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>