staging: comedi: adl_pci9118: tidy up pci9118_set_chanlist()

Define some macros to set the 'chan' and 'range' bits in the chanlist
register. Use them to tidy up this 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>