dt-bindings: input: touchscreen: convert colibri-vf50-ts.txt to yaml

Convert binding doc colibri-vf50-ts.txt to yaml.
Additional change:
- add ref touchscreen.yaml.
- remove standard pinctrl properties.

Fix below warning:
arch/arm64/boot/dts/freescale/imx8qm-apalis-eval.dtb: /touchscreen:
failed to match any schema with compatible: ['toradex,vf50-touchscreen']

Reviewed-by: Rob Herring (Arm) <[e-mail]>
Signed-off-by: Frank Li <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/touchscreen/colibri-vf50-ts.txt

···
-* Toradex Colibri VF50 Touchscreen driver
-
-Required Properties:
-- compatible must be toradex,vf50-touchscreen
-- io-channels: adc channels being used by the Colibri VF50 module
-    IIO ADC for Y-, X-, Y+, X+ connections
-- xp-gpios: FET gate driver for input of X+
-- xm-gpios: FET gate driver for input of X-
-- yp-gpios: FET gate driver for input of Y+
-- ym-gpios: FET gate driver for input of Y-
-- interrupts: pen irq interrupt for touch detection, signal from X plate
-- pinctrl-names: "idle", "default"
-- pinctrl-0: pinctrl node for pen/touch detection, pinctrl must provide
-    pull-up resistor on X+, X-.
-- pinctrl-1: pinctrl node for X/Y and pressure measurement (ADC) state pinmux
-- vf50-ts-min-pressure: pressure level at which to stop measuring X/Y values
-
-Example:
-
-	touchctrl: vf50_touchctrl {
-		compatible = "toradex,vf50-touchscreen";
-		io-channels = <&adc1 0>,<&adc0 0>,
-				<&adc0 1>,<&adc1 2>;
-		xp-gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
-		xm-gpios = <&gpio2 29 GPIO_ACTIVE_HIGH>;
-		yp-gpios = <&gpio0 12 GPIO_ACTIVE_LOW>;
-		ym-gpios = <&gpio0 4 GPIO_ACTIVE_HIGH>;
-		interrupt-parent = <&gpio0>;
-		interrupts = <8 IRQ_TYPE_LEVEL_LOW>;
-		pinctrl-names = "idle","default";
-		pinctrl-0 = <&pinctrl_touchctrl_idle>, <&pinctrl_touchctrl_gpios>;
-		pinctrl-1 = <&pinctrl_touchctrl_default>, <&pinctrl_touchctrl_gpios>;
-		vf50-ts-min-pressure = <200>;
-	};

Documentation/devicetree/bindings/input/touchscreen/toradex,vf50-touchscreen.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/toradex,vf50-touchscreen.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Toradex Colibri VF50 Touchscreen
+
+maintainers:
+  - Dmitry Torokhov <[e-mail]>
+  - Sanchayan Maity <[e-mail]>
+
+properties:
+  compatible:
+    const: toradex,vf50-touchscreen
+
+  interrupts:
+    maxItems: 1
+
+  io-channels:
+    maxItems: 4
+    description:
+      adc channels being used by the Colibri VF50 module
+      IIO ADC for Y-, X-, Y+, X+ connections
+
+  xp-gpios:
+    description: FET gate driver for input of X+
+
+  xm-gpios:
+    description: FET gate driver for input of X-
+
+  yp-gpios:
+    description: FET gate driver for input of Y+
+
+  ym-gpios:
+    description: FET gate driver for input of Y-
+
+  vf50-ts-min-pressure:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 50
+    maximum: 2000
+    description: pressure level at which to stop measuring X/Y values
+
+required:
+  - compatible
+  - io-channels
+  - xp-gpios
+  - xm-gpios
+  - yp-gpios
+  - ym-gpios
+  - interrupts
+  - vf50-ts-min-pressure
+
+allOf:
+  - $ref: touchscreen.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/gpio/gpio.h>
+
+    touchscreen {
+        compatible = "toradex,vf50-touchscreen";
+        interrupt-parent = <&gpio0>;
+        interrupts = <8 IRQ_TYPE_LEVEL_LOW>;
+        io-channels = <&adc1 0>, <&adc0 0>, <&adc0 1>, <&adc1 2>;
+        xp-gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
+        xm-gpios = <&gpio2 29 GPIO_ACTIVE_HIGH>;
+        yp-gpios = <&gpio0 12 GPIO_ACTIVE_LOW>;
+        ym-gpios = <&gpio0 4 GPIO_ACTIVE_HIGH>;
+        pinctrl-names = "idle", "default";
+        pinctrl-0 = <&pinctrl_touchctrl_idle>, <&pinctrl_touchctrl_gpios>;
+        pinctrl-1 = <&pinctrl_touchctrl_default>, <&pinctrl_touchctrl_gpios>;
+        vf50-ts-min-pressure = <200>;
+    };