dt-bindings: input: Convert mpr121 binding to json-schema

Convert the mpr121 binding to DT schema format using json-schema.
Signed-off-by: Michal Vokáč <michal.vokac@ysoft.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/fsl,mpr121-touchkey.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/fsl,mpr121-touchkey.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Freescale MPR121 capacitive touch sensor controller
+
+maintainers:
+  - Dmitry Torokhov <dmitry.torokhov@gmail.com>
+
+description: |
+  The MPR121 supports up to 12 completely independent electrodes/capacitance
+  sensing inputs in which 8 are multifunctional for LED driving and GPIO.
+  https://www.nxp.com/docs/en/data-sheet/MPR121.pdf
+
+allOf:
+  - $ref: input.yaml#
+
+properties:
+  compatible:
+    const: fsl,mpr121-touchkey
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  vdd-supply:
+    maxItems: 1
+
+  linux,keycodes:
+    minItems: 1
+    maxItems: 12
+
+  wakeup-source:
+    description: Use any event on keypad as wakeup event.
+    type: boolean
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - vdd-supply
+  - linux,keycodes
+
+examples:
+  - |
+    #include "dt-bindings/input/input.h"
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        mpr121@5a {
+            compatible = "fsl,mpr121-touchkey";
+            reg = <0x5a>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <28 2>;
+            autorepeat;
+            vdd-supply = <&ldo4_reg>;
+            linux,keycodes = <KEY_0>, <KEY_1>, <KEY_2>, <KEY_3>,
+                             <KEY_4>, <KEY_5>, <KEY_6>, <KEY_7>,
+                             <KEY_8>, <KEY_9>, <KEY_A>, <KEY_B>;
+        };
+    };

Documentation/devicetree/bindings/input/mpr121-touchkey.txt

-* Freescale MPR121 Controllor
-
-Required Properties:
-- compatible:		Should be "fsl,mpr121-touchkey"
-- reg:			The I2C slave address of the device.
-- interrupts:		The interrupt number to the cpu.
-- vdd-supply:		Phandle to the Vdd power supply.
-- linux,keycodes:	Specifies an array of numeric keycode values to
-			be used for reporting button presses. The array can
-			contain up to 12 entries.
-
-Optional Properties:
-- wakeup-source:	Use any event on keypad as wakeup event.
-- autorepeat:		Enable autorepeat feature.
-
-Example:
-
-#include "dt-bindings/input/input.h"
-
-	touchkey: mpr121@5a {
-		compatible = "fsl,mpr121-touchkey";
-		reg = <0x5a>;
-		interrupt-parent = <&gpio1>;
-		interrupts = <28 2>;
-		autorepeat;
-		vdd-supply = <&ldo4_reg>;
-		linux,keycodes = <KEY_0>, <KEY_1>, <KEY_2>, <KEY_3>,
-				<KEY_4> <KEY_5>, <KEY_6>, <KEY_7>,
-				<KEY_8>, <KEY_9>, <KEY_A>, <KEY_B>;
-	};