linux-imx

drm: rcar-du: Switch page flip to atomic helpers

The atomic page flip helper implements the page flip operation using
asynchronous commits.

As the legacy page flip was the last CRTC operation that needed direct
access to plane setup, the plane setup functions can now become private
to the plane implementation.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>