staging: comedi: c6xdigio: remove commented out subdevice code

The code to initialize subdevice[2] is commented out and incomplete.
Just remove it.

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>