staging: comedi: amplc_dio200.h: remove unnecessary function comment descriptions

The function names provide enough description. The extra comments are not
necessary. Remove them.

Also, tidy up some of the function declarations.
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>