linux-phytec-ti

drm: rcar-du: Output the DISP signal on the DISP pin

The DE signal is currently configured to be identical to the DISP
signal and is used for the same purpose. To make it clearer that the
DISP pin outputs the DISP signal, select it explicitly.

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