staging: comedi: rtd520: remove unnecessary comments from rtd_ao_winsn()

These comments are cut-and-paste from the old skeleton driver. 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>