dt-bindings: input: convert lpc32xx-key.txt to yaml format

Convert lpc32xx-key.txt to yaml format.

Additional changes:
- set maximum of key-row(column) to 4.
- add ref to matrix-keymap.yaml.

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

Documentation/devicetree/bindings/input/lpc32xx-key.txt

···
-NXP LPC32xx Key Scan Interface
-
-This binding is based on the matrix-keymap binding with the following
-changes:
-
-Required Properties:
-- compatible: Should be "nxp,lpc3220-key"
-- reg: Physical base address of the controller and length of memory mapped
-  region.
-- interrupts: The interrupt number to the cpu.
-- clocks: phandle to clock controller plus clock-specifier pair
-- nxp,debounce-delay-ms: Debounce delay in ms
-- nxp,scan-delay-ms: Repeated scan period in ms
-- linux,keymap: the key-code to be reported when the key is pressed
-  and released, see also
-  Documentation/devicetree/bindings/input/matrix-keymap.txt
-
-Note: keypad,num-rows and keypad,num-columns are required, and must be equal
-since LPC32xx only supports square matrices
-
-Example:
-
-	key@40050000 {
-		compatible = "nxp,lpc3220-key";
-		reg = <0x40050000 0x1000>;
-		clocks = <&clk LPC32XX_CLK_KEY>;
-		interrupt-parent = <&sic1>;
-		interrupts = <22 IRQ_TYPE_LEVEL_HIGH>;
-		keypad,num-rows = <1>;
-		keypad,num-columns = <1>;
-		nxp,debounce-delay-ms = <3>;
-		nxp,scan-delay-ms = <34>;
-		linux,keymap = <0x00000002>;
-	};

Documentation/devicetree/bindings/input/nxp,lpc3220-key.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/nxp,lpc3220-key.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP LPC32xx Key Scan Interface
+
+maintainers:
+  - Frank Li <[e-mail]>
+
+properties:
+  compatible:
+    const: nxp,lpc3220-key
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  nxp,debounce-delay-ms:
+    description: Debounce delay in ms
+
+  nxp,scan-delay-ms:
+    description: Repeated scan period in ms
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - nxp,debounce-delay-ms
+  - nxp,scan-delay-ms
+  - linux,keymap
+
+allOf:
+  - $ref: matrix-keymap.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/clock/lpc32xx-clock.h>
+
+    key@40050000 {
+        compatible = "nxp,lpc3220-key";
+        reg = <0x40050000 0x1000>;
+        clocks = <&clk LPC32XX_CLK_KEY>;
+        interrupt-parent = <&sic1>;
+        interrupts = <22 IRQ_TYPE_LEVEL_HIGH>;
+        keypad,num-rows = <1>;
+        keypad,num-columns = <1>;
+        nxp,debounce-delay-ms = <3>;
+        nxp,scan-delay-ms = <34>;
+        linux,keymap = <0x00000002>;
+    };