dt-bindings: display: Add compatible for A64 DE2 display pipeline

Allwinner A64 has a DE2 display pipeline. The TCONs are similar to the
ones in A83T, but the mixers are new (similar to the later R40 SoC).

This patch adds dt-binding documentation for A64 DE2 display pipeline.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Rob Herring <robh@kernel.org>
[Icenowy: Refactor and also cover TCON1]
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180904044053.15425-4-icenowy@aosc.io

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

@@ -151,6 +151,8 @@ Required properties:
    * allwinner,sun8i-v3s-tcon
    * allwinner,sun9i-a80-tcon-lcd
    * 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"
  - reg: base address and size of memory-mapped region
  - interrupts: interrupt associated to this IP
  - clocks: phandles to the clocks feeding the TCON.
@@ -370,6 +372,8 @@ Required properties:
     * allwinner,sun8i-a83t-de2-mixer-1
     * allwinner,sun8i-h3-de2-mixer-0
     * allwinner,sun8i-v3s-de2-mixer
+    * allwinner,sun50i-a64-de2-mixer-0
+    * allwinner,sun50i-a64-de2-mixer-1
   - reg: base address and size of the memory-mapped region.
   - clocks: phandles to the clocks feeding the mixer
     * bus: the mixer interface clock
@@ -403,6 +407,7 @@ Required properties:
     * allwinner,sun8i-r40-display-engine
     * allwinner,sun8i-v3s-display-engine
     * allwinner,sun9i-a80-display-engine
+    * allwinner,sun50i-a64-display-engine
 
   - allwinner,pipelines: list of phandle to the display engine
     frontends (DE 1.0) or mixers (DE 2.0) available.