staging: comedi: cb_pcidas: use comedi_range_is_unipolar()

Instead of relying on the IS_UNIPOLAR mask value, use the comedi
helper function to check if the range is unipolar.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 file changed