staging: wfx: dual CTS is never necessary

Dual CTS is only necessary when sending/receiving STBC data. However,
the chip does not support STBC, so it is never necessary to enable
double CTS.

We can simplify the code.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200420160311.57323-7-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>