staging: comedi: cb_pcimdas: update driver comment

The Comedi driver comment mentions a couple of manual configuration
options, but manual configuration via the COMEDI_DEVCONFIG ioctl and
comedi "attach" handler is no longer supported by this driver.  Update
the comment appropriately.

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