staging: comedi: adl_pci9118: remove 'n_aochan' boardinfo

This member of the boardinfo is the same for all entries. Remove it.

Also, remove the initialization of the subdevice 'len_chanlist'. This
member is only used if the subdevice supports async commands.

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>