dt-bindings: display: convert ilitek,ili9881c to DT Schema

Updating this binding identified an issue in the example in
the allwinner,sun6i-a31-mipi-dsi binding.
Fix the example so no new warnings are introduced.

v2:
  - fix example in allwinner,sun6i-a31-mipi-dsi (Rob)
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200408195109.32692-9-sam@ravnborg.org

Documentation/devicetree/bindings/display/allwinner,sun6i-a31-mipi-dsi.yaml

@@ -119,7 +119,7 @@ examples:
         panel@0 {
                 compatible = "bananapi,lhr050h41", "ilitek,ili9881c";
                 reg = <0>;
-                power-gpios = <&pio 1 7 0>; /* PB07 */
+                power-supply = <&reg_display>;
                 reset-gpios = <&r_pio 0 5 1>; /* PL05 */
                 backlight = <&pwm_bl>;
         };

Documentation/devicetree/bindings/display/panel/ilitek,ili9881c.txt

-Ilitek ILI9881c based MIPI-DSI panels
-
-Required properties:
-  - compatible: must be "ilitek,ili9881c" and one of:
-    * "bananapi,lhr050h41"
-  - reg: DSI virtual channel used by that screen
-  - power-supply: phandle to the power regulator
-  - reset-gpios: a GPIO phandle for the reset pin
-
-Optional properties:
-  - backlight: phandle to the backlight used
-
-Example:
-panel@0 {
-	compatible = "bananapi,lhr050h41", "ilitek,ili9881c";
-	reg = <0>;
-	power-supply = <&reg_display>;
-	reset-gpios = <&r_pio 0 5 GPIO_ACTIVE_LOW>; /* PL05 */
-	backlight = <&pwm_bl>;
-};

Documentation/devicetree/bindings/display/panel/ilitek,ili9881c.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/ilitek,ili9881c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Ilitek ILI9881c based MIPI-DSI panels
+
+maintainers:
+  - Maxime Ripard <mripard@kernel.org>
+
+properties:
+  compatible:
+    items:
+      - enum:
+        - bananapi,lhr050h41
+
+      - const: ilitek,ili9881c
+
+  backlight: true
+  power-supply: true
+  reg: true
+  reset-gpios: true
+
+required:
+  - compatible
+  - power-supply
+  - reg
+  - reset-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    dsi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        panel@0 {
+            compatible = "bananapi,lhr050h41", "ilitek,ili9881c";
+            reg = <0>;
+            power-supply = <&reg_display>;
+            reset-gpios = <&r_pio 0 5 GPIO_ACTIVE_LOW>; /* PL05 */
+            backlight = <&pwm_bl>;
+        };
+    };
+
+...