dt-bindings: display: convert lgphilips,lb035q02 to DT Schema

v2:
  - drop use of spi-slave.yaml (Maxime)
  - added unevaluatedProperties (maxime)
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200408195109.32692-35-sam@ravnborg.org

Documentation/devicetree/bindings/display/panel/lgphilips,lb035q02.txt

-LG.Philips LB035Q02 Panel
-=========================
-
-Required properties:
-- compatible: "lgphilips,lb035q02"
-- enable-gpios: panel enable gpio
-
-Optional properties:
-- label: a symbolic name for the panel
-
-Required nodes:
-- Video port for DPI input
-
-Example
--------
-
-lcd-panel: panel@0 {
-	compatible = "lgphilips,lb035q02";
-	reg = <0>;
-	spi-max-frequency = <100000>;
-	spi-cpol;
-	spi-cpha;
-
-	label = "lcd";
-
-	enable-gpios = <&gpio7 7 0>;
-
-	port {
-		lcd_in: endpoint {
-			remote-endpoint = <&dpi_out>;
-		};
-	};
-};

Documentation/devicetree/bindings/display/panel/lgphilips,lb035q02.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/lgphilips,lb035q02.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: LG.Philips LB035Q02 Panel
+
+description: |
+  The panel must obey the rules for a SPI slave device as specified in
+  spi/spi-controller.yaml
+
+maintainers:
+  - Tomi Valkeinen <tomi.valkeinen@ti.com>
+
+allOf:
+  - $ref: panel-common.yaml#
+
+properties:
+  compatible:
+    const: lgphilips,lb035q02
+
+  label: true
+  enable-gpios: true
+  port: true
+
+required:
+  - compatible
+  - enable-gpios
+  - port
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        panel: panel@0 {
+            compatible = "lgphilips,lb035q02";
+            reg = <0>;
+            spi-max-frequency = <100000>;
+            spi-cpol;
+            spi-cpha;
+
+            label = "lcd";
+
+            enable-gpios = <&gpio7 7 0>;
+
+            port {
+                lcd_in: endpoint {
+                    remote-endpoint = <&dpi_out>;
+                };
+            };
+        };
+    };
+
+...