staging: comedi: adv_pci1710: tidy up setup_channel_list()

Rename this function so it has namespace associated with the driver.

Tidy up the code to clarify the function. Remove the unnecessary static const
array muxonechan[].

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>