dt-bindings: timer: Convert i.MX SYSCTR to json-schema

Convert the i.MX SYSCTR binding to DT schema format using json-schema.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt

-NXP System Counter Module(sys_ctr)
-
-The system counter(sys_ctr) is a programmable system counter which provides
-a shared time base to Cortex A15, A7, A53, A73, etc. it is intended for use in
-applications where the counter is always powered and support multiple,
-unrelated clocks. The compare frame inside can be used for timer purpose.
-
-Required properties:
-
-- compatible :      should be "nxp,sysctr-timer"
-- reg :             Specifies the base physical address and size of the comapre
-                    frame and the counter control, read & compare.
-- interrupts :      should be the first compare frames' interrupt
-- clocks : 	    Specifies the counter clock.
-- clock-names: 	    Specifies the clock's name of this module
-
-Example:
-
-	system_counter: timer@306a0000 {
-		compatible = "nxp,sysctr-timer";
-		reg = <0x306a0000 0x20000>;/* system-counter-rd & compare */
-		clocks = <&clk_8m>;
-		clock-names = "per";
-		interrupts = <GIC_SPI 47 IRQ_TYPE_LEVEL_HIGH>;
-	};

Documentation/devicetree/bindings/timer/nxp,sysctr-timer.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/nxp,sysctr-timer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP System Counter Module(sys_ctr)
+
+maintainers:
+  - Bai Ping <ping.bai@nxp.com>
+
+description: |
+  The system counter(sys_ctr) is a programmable system counter
+  which provides a shared time base to Cortex A15, A7, A53, A73,
+  etc. it is intended for use in applications where the counter
+  is always powered and support multiple, unrelated clocks. The
+  compare frame inside can be used for timer purpose.
+
+properties:
+  compatible:
+    const: nxp,sysctr-timer
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    const: per
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    timer@306a0000 {
+        compatible = "nxp,sysctr-timer";
+        reg = <0x306a0000 0x20000>;
+        clocks = <&clk_8m>;
+        clock-names = "per";
+        interrupts = <GIC_SPI 47 IRQ_TYPE_LEVEL_HIGH>;
+     };