staging: comedi: adl_pci9111: remove chanlist_len checks

The chanlist_len is validated by the comedi core before calling
the do_cmdtest function. Remove these redundant checks.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>