dt-bindings: mmc: Convert imx mmc to json-schema

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

Documentation/devicetree/bindings/mmc/fsl-imx-mmc.txt

-* Freescale Secure Digital Host Controller for i.MX2/3 series
-
-This file documents differences to the properties defined in mmc.txt.
-
-Required properties:
-- compatible : Should be "fsl,<chip>-mmc", chip can be imx21 or imx31
-
-Optional properties:
-- dmas: One DMA phandle with arguments as defined by the devicetree bindings
-	of the used DMA controller.
-- dma-names: Has to be "rx-tx".
-
-Example:
-
-sdhci1: sdhci@10014000 {
-	compatible = "fsl,imx27-mmc", "fsl,imx21-mmc";
-	reg = <0x10014000 0x1000>;
-	interrupts = <11>;
-	dmas = <&dma 7>;
-	dma-names = "rx-tx";
-	bus-width = <4>;
-	cd-gpios = <&gpio3 29>;
-};

Documentation/devicetree/bindings/mmc/fsl-imx-mmc.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mmc/fsl-imx-mmc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Freescale Secure Digital Host Controller for i.MX2/3 series
+
+maintainers:
+  - Markus Pargmann <mpa@pengutronix.de>
+
+allOf:
+  - $ref: "mmc-controller.yaml"
+
+properties:
+  compatible:
+    oneOf:
+      - const: fsl,imx21-mmc
+      - const: fsl,imx31-mmc
+      - items:
+          - const: fsl,imx27-mmc
+          - const: fsl,imx21-mmc
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  dmas:
+    maxItems: 1
+
+  dma-names:
+    const: rx-tx
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    mmc@10014000 {
+        compatible = "fsl,imx27-mmc", "fsl,imx21-mmc";
+        reg = <0x10014000 0x1000>;
+        interrupts = <11>;
+        dmas = <&dma 7>;
+        dma-names = "rx-tx";
+        bus-width = <4>;
+        cd-gpios = <&gpio3 29>;
+    };