staging: comedi: pcl816: remove 'ai_act_chanlist_{len, pos}' from private data

These members of the private data don't do anything usefull. Just remove them.

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>