dt-bindings: display: sun4i-drm: Add H6 display engine compatibles

This commit adds compatibles used in H6 display pipeline, namely for
display engine, mixer and TV TCON.

H6 display engine is somewhat similar to R40, just less TCONs and
mixer support more features.
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181104182705.18047-8-jernej.skrabec@siol.net

Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt

@@ -158,6 +158,7 @@ Required properties:
    * allwinner,sun9i-a80-tcon-tv
    * "allwinner,sun50i-a64-tcon-lcd", "allwinner,sun8i-a83t-tcon-lcd"
    * "allwinner,sun50i-a64-tcon-tv", "allwinner,sun8i-a83t-tcon-tv"
+   * allwinner,sun50i-h6-tcon-tv, allwinner,sun8i-r40-tcon-tv
  - reg: base address and size of memory-mapped region
  - interrupts: interrupt associated to this IP
  - clocks: phandles to the clocks feeding the TCON.
@@ -381,6 +382,7 @@ Required properties:
     * allwinner,sun8i-v3s-de2-mixer
     * allwinner,sun50i-a64-de2-mixer-0
     * allwinner,sun50i-a64-de2-mixer-1
+    * allwinner,sun50i-h6-de3-mixer-0
   - reg: base address and size of the memory-mapped region.
   - clocks: phandles to the clocks feeding the mixer
     * bus: the mixer interface clock
@@ -415,9 +417,10 @@ Required properties:
     * allwinner,sun8i-v3s-display-engine
     * allwinner,sun9i-a80-display-engine
     * allwinner,sun50i-a64-display-engine
+    * allwinner,sun50i-h6-display-engine
 
   - allwinner,pipelines: list of phandle to the display engine
-    frontends (DE 1.0) or mixers (DE 2.0) available.
+    frontends (DE 1.0) or mixers (DE 2.0/3.0) available.
 
 Example: