staging: comedi: adl_pci9118: remove PCI9118_CHANLEN

This define is only used to initialize the analog input sudevice
'len_chanlist'. Remove the define and just open code the value.

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>