drm/sun4i: Add support for A64 display engine

Display Engine(DE2) in Allwinner A64 has two mixers and tcons.

The routing for mixer0 is through tcon0 and connected to
LVDS/RGB/MIPI-DSI controller.

The routing for mixer1 is through tcon1 and connected to HDMI.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180904044053.15425-6-icenowy@aosc.io

drivers/gpu/drm/sun4i/sun4i_drv.c

@@ -405,6 +405,7 @@ static const struct of_device_id sun4i_drv_of_table[] = {
 	{ .compatible = "allwinner,sun8i-r40-display-engine" },
 	{ .compatible = "allwinner,sun8i-v3s-display-engine" },
 	{ .compatible = "allwinner,sun9i-a80-display-engine" },
+	{ .compatible = "allwinner,sun50i-a64-display-engine" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, sun4i_drv_of_table);