staging: comedi: addi_apci_3120: remove unipolar range from analog outputs

staging: comedi: addi_apci_3120: remove unipolar range from analog outputs

The analog outputs of the APCI-3120 have a 14-bit bipolar range and use straight
binary values (0x0000 = -10V to 0x3fff = +10V) to set the outputs. This driver
tries to fake a unipolar range by munging the comedi data values to only output
0V to +10V signals (0x0000 to 0x1fff values are munged to 0x2000 - 0x3fff).

This causes problems with the comedilib API functions that convert between comedi
values and physical values. It's also possible for the user to pass a data value
that would get munged and actually change the wrong channel.

Fix this by change the subdevice range_table to range_bipolar10 and remove the
munging in apci3120_ao_insn_write().

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>