staging: comedi: adv_pci_dio: tidy up the comedi comment block

The Description is a bit long winded and the same information is in
the Devices. Shorten the Description and tidy up the Devices.

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>