staging: comedi: usbduxsigma: use comedi provided range_unipolar2_5

Remove the private range, range_usbdux_ao_range, in this driver and use
the comedi provided range_unipolar2_5 instead.

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

diff --cc drivers/staging/comedi/drivers/usbduxsigma.c
Simple merge