dt-bindings: drm/bridge: analogix-anx78xx: add new variants

Add support for the analogix,anx7808, analogix,anx7812, and
analogix,anx7818 variants.
Signed-off-by: Brian Masney <masneyb@onstation.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190815004854.19860-2-masneyb@onstation.org

Documentation/devicetree/bindings/display/bridge/anx7814.txt

@@ -6,7 +6,11 @@ designed for portable devices.
 
 Required properties:
 
- - compatible		: "analogix,anx7814"
+ - compatible		: Must be one of:
+			  "analogix,anx7808"
+			  "analogix,anx7812"
+			  "analogix,anx7814"
+			  "analogix,anx7818"
  - reg			: I2C address of the device
  - interrupts		: Should contain the INTP interrupt
  - hpd-gpios		: Which GPIO to use for hpd