staging: vt6656: rxtx: move tx_context->fb_option into function structure.

Replace fb_option in function calls with tx_context->fb_option.

Namely functions s_vFillCTSHead and s_vFillRTSHead

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