dt-bindings: display: convert ilitek,ili9322 to DT Schema

The .txt binding explains:

"
    The following optional properties only apply to
    RGB and YUV input modes and
    can be omitted for BT.656 input modes:
"

This constraint is not implmented in the DT Schema.

The original binding from the .txt file referenced
properties that is included in panel-timing.yaml.

The properties in question are:
  - pixelclk-active
  - de-active
  - hsync-active
  - vsync-active

These properties was dropped in the conversion as they are not relevant.

v2:
  - drop properties from panel-timing (Linus)
  - drop use of spi-slave.yaml (Maxime)
  - introduce unevaluatedProperties (Maxime)
  - dropped unused properties (Linus)
  - delete stray spaces
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200408195109.32692-8-sam@ravnborg.org

Documentation/devicetree/bindings/display/panel/ilitek,ili9322.txt

-Ilitek ILI9322 TFT panel driver with SPI control bus
-
-This is a driver for 320x240 TFT panels, accepting a variety of input
-streams that get adapted and scaled to the panel. The panel output has
-960 TFT source driver pins and 240 TFT gate driver pins, VCOM, VCOML and
-VCOMH outputs.
-
-Required properties:
-  - compatible: "dlink,dir-685-panel", "ilitek,ili9322"
-    (full system-specific compatible is always required to look up configuration)
-  - reg: address of the panel on the SPI bus
-
-Optional properties:
-  - vcc-supply: core voltage supply, see regulator/regulator.txt
-  - iovcc-supply: voltage supply for the interface input/output signals,
-    see regulator/regulator.txt
-  - vci-supply: voltage supply for analog parts, see regulator/regulator.txt
-  - reset-gpios: a GPIO spec for the reset pin, see gpio/gpio.txt
-
-  The following optional properties only apply to RGB and YUV input modes and
-  can be omitted for BT.656 input modes:
-
-  - pixelclk-active: see display/panel/display-timing.txt
-  - de-active: see display/panel/display-timing.txt
-  - hsync-active: see display/panel/display-timing.txt
-  - vsync-active: see display/panel/display-timing.txt
-
-The panel must obey the rules for a SPI slave device as specified in
-spi/spi-bus.txt
-
-The device node can contain one 'port' child node with one child
-'endpoint' node, according to the bindings defined in
-media/video-interfaces.txt. This node should describe panel's video bus.
-
-Example:
-
-panel: display@0 {
-	compatible = "dlink,dir-685-panel", "ilitek,ili9322";
-	reg = <0>;
-	vcc-supply = <&vdisp>;
-	iovcc-supply = <&vdisp>;
-	vci-supply = <&vdisp>;
-
-	port {
-		panel_in: endpoint {
-			remote-endpoint = <&display_out>;
-		};
-	};
-};

Documentation/devicetree/bindings/display/panel/ilitek,ili9322.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/ilitek,ili9322.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Ilitek ILI9322 TFT panel driver with SPI control bus
+
+maintainers:
+  - Linus Walleij <linus.walleij@linaro.org>
+
+description: |
+  This is a driver for 320x240 TFT panels, accepting a variety of input
+  streams that get adapted and scaled to the panel. The panel output has
+  960 TFT source driver pins and 240 TFT gate driver pins, VCOM, VCOML and
+  VCOMH outputs.
+
+  The panel must obey the rules for a SPI slave device as specified in
+  spi/spi-controller.yaml
+
+allOf:
+  - $ref: panel-common.yaml#
+
+properties:
+  compatible:
+    items:
+      - enum:
+        - dlink,dir-685-panel
+
+      - const: ilitek,ili9322
+
+  reset-gpios: true
+  port: true
+
+  vcc-supply:
+    description: Core voltage supply
+
+  iovcc-supply:
+    description: Voltage supply for the interface input/output signals
+
+  vci-supply:
+    description: Voltage supply for analog parts
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        panel: display@0 {
+            compatible = "dlink,dir-685-panel", "ilitek,ili9322";
+            reg = <0>;
+            vcc-supply = <&vdisp>;
+            iovcc-supply = <&vdisp>;
+            vci-supply = <&vdisp>;
+
+            port {
+                panel_in: endpoint {
+                    remote-endpoint = <&display_out>;
+                };
+            };
+        };
+    };
+
+...