staging: comedi: c6xdigio: tidy up subdevice 0 init

This subdevice is a PWM output not and analog output, fix the 'type'.

Fix the subdevice 'range', range_bipolar does not make sense for a PWM
output. The range_unknown is a better choice.

Remove the commented out init of the 'trig'.

For aesthetics, add some whitespace to the init and rename the 'insn_write'
function.

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>