staging: comedi: pcl724: fix 96 DIO configuration option

According to the comedi documentation at the beginning of the file,
configuration option 2 sets the number of DIO channels on the boards
that support 144 or 96 channels.

Fix the (*attach) to use the correct configuration option.

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>