dt-bindings: display: convert innolux,p120zdg-bf1 to DT Schema

v3:
  - Fix stray spaces
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Sandeep Panda <spanda@codeaurora.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200408195109.32692-12-sam@ravnborg.org

Documentation/devicetree/bindings/display/panel/innolux,p120zdg-bf1.txt

-Innolux P120ZDG-BF1 12.02 inch eDP 2K display panel
-
-This binding is compatible with the simple-panel binding, which is specified
-in simple-panel.txt in this directory.
-
-Required properties:
-- compatible: should be "innolux,p120zdg-bf1"
-- power-supply: regulator to provide the supply voltage
-
-Optional properties:
-- enable-gpios: GPIO pin to enable or disable the panel
-- backlight: phandle of the backlight device attached to the panel
-- no-hpd: If HPD isn't hooked up; add this property.
-
-Example:
-	panel_edp: panel-edp {
-		compatible = "innolux,p120zdg-bf1";
-		enable-gpios = <&msmgpio 31 GPIO_ACTIVE_LOW>;
-		power-supply = <&pm8916_l2>;
-		backlight = <&backlight>;
-		no-hpd;
-	};

Documentation/devicetree/bindings/display/panel/innolux,p120zdg-bf1.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/innolux,p120zdg-bf1.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Innolux P120ZDG-BF1 12.02 inch eDP 2K display panel
+
+maintainers:
+  - Sandeep Panda <spanda@codeaurora.org>
+  - Douglas Anderson <dianders@chromium.org>
+
+allOf:
+  - $ref: panel-common.yaml#
+
+properties:
+  compatible:
+    const: innolux,p120zdg-bf1
+
+  enable-gpios: true
+  power-supply: true
+  backlight: true
+  no-hpd: true
+
+required:
+  - compatible
+  - power-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    panel_edp: panel-edp {
+        compatible = "innolux,p120zdg-bf1";
+        enable-gpios = <&msmgpio 31 GPIO_ACTIVE_LOW>;
+        power-supply = <&pm8916_l2>;
+        backlight = <&backlight>;
+        no-hpd;
+    };
+
+...