media: dt-bindings: video-interfaces: add defines for sampling modes

media: dt-bindings: video-interfaces: add defines for sampling modes

Add defines for the pixel clock sampling modes (rising edge, falling edge,
dual edge) for parallel video interfaces.
This avoids hardcoded constants in device tree sources.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Michael Riesch <michael.riesch@wolfvision.net>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Michael Riesch <michael.riesch@collabora.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>