dt-bindings: fsl: Convert i.MX7ULP PM to json-schema

Convert the i.MX7ULP PM binding to DT schema format using json-schema.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1596595841-27563-1-git-send-email-Anson.Huang@nxp.comSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/freescale/fsl,imx7ulp-pm.txt

-Freescale i.MX7ULP Power Management Components
-----------------------------------------------
-
-The Multi-System Mode Controller (MSMC) is responsible for sequencing
-the MCU into and out of all stop and run power modes. Specifically, it
-monitors events to trigger transitions between power modes while
-controlling the power, clocks, and memories of the MCU to achieve the
-power consumption and functionality of that mode.
-
-The WFI or WFE instruction is used to invoke a Sleep, Deep Sleep or
-Standby modes for either Cortex family. Run, Wait, and Stop are the
-common terms used for the primary operating modes of Kinetis
-microcontrollers.
-
-Required properties:
-- compatible:	Should be "fsl,imx7ulp-smc1".
-- reg:		Specifies base physical address and size of the register sets.
-
-Example:
-smc1: smc1@40410000 {
-	compatible = "fsl,imx7ulp-smc1";
-	reg = <0x40410000 0x1000>;
-};

Documentation/devicetree/bindings/arm/freescale/fsl,imx7ulp-pm.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/freescale/fsl,imx7ulp-pm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Freescale i.MX7ULP Power Management Components
+
+maintainers:
+  - A.s. Dong <aisheng.dong@nxp.com>
+
+description: |
+  The Multi-System Mode Controller (MSMC) is responsible for sequencing
+  the MCU into and out of all stop and run power modes. Specifically, it
+  monitors events to trigger transitions between power modes while
+  controlling the power, clocks, and memories of the MCU to achieve the
+  power consumption and functionality of that mode.
+
+  The WFI or WFE instruction is used to invoke a Sleep, Deep Sleep or
+  Standby modes for either Cortex family. Run, Wait, and Stop are the
+  common terms used for the primary operating modes of Kinetis
+  microcontrollers.
+
+properties:
+  compatible:
+    const: fsl,imx7ulp-smc1
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    smc1@40410000 {
+        compatible = "fsl,imx7ulp-smc1";
+        reg = <0x40410000 0x1000>;
+    };