staging: comedi: adl_pci9118: remove 'n_aichand' boardinfo

This member of the boardinfo is the same for all entries. It's also
half the subdevice 'n_chan'. Use that instead and remove the boardinfo.

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>