staging: comedi: me_daq: simplify analog output boardinfo

The boards supported by this driver either have analog outputs or don't
have them. Add a new boardinfo value, 'has_ao', to indicate this.

The boards that have analog outputs always have 4, 12-bit channels. Remove
the unnecessary boardinfo and just open-code the values in the subdevice
initialization.

The boards with analog outputs also share the same output range capabilities.
Rename the comedi_lrange to make it common for all board types.

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>