staging: comedi: rtd520: convert DAC register defines to macros

For aesthetics, convert the defines for the various DAC registers into
macros that take the comedi channel and return the correct offset.

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>
1 file changed