drm: rcar-du: Enable the atomic updates API
drm: rcar-du: Enable the atomic updates API

Set the DRIVER_ATOMIC flag to enable usage of the atomic updates API
with the driver.

Signed-off-by: Laurent Pinchart <ae960578cc5eca7b9b1dbc37d9caa6cb634f35e0@ideasonboard.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs