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

Convert the MXS MMC binding to DT schema format using json-schema
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1591234886-15351-4-git-send-email-Anson.Huang@nxp.comSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/mmc/mxs-mmc.txt

-* Freescale MXS MMC controller
-
-The Freescale MXS Synchronous Serial Ports (SSP) can act as a MMC controller
-to support MMC, SD, and SDIO types of memory cards.
-
-This file documents differences between the core properties in mmc.txt
-and the properties used by the mxsmmc driver.
-
-Required properties:
-- compatible: Should be "fsl,<chip>-mmc".  The supported chips include
-  imx23 and imx28.
-- interrupts: Should contain ERROR interrupt number
-- dmas: DMA specifier, consisting of a phandle to DMA controller node
-  and SSP DMA channel ID.
-  Refer to dma.txt and fsl-mxs-dma.txt for details.
-- dma-names: Must be "rx-tx".
-
-Examples:
-
-ssp0: ssp@80010000 {
-	compatible = "fsl,imx28-mmc";
-	reg = <0x80010000 2000>;
-	interrupts = <96>;
-	dmas = <&dma_apbh 0>;
-	dma-names = "rx-tx";
-	bus-width = <8>;
-};

Documentation/devicetree/bindings/mmc/mxs-mmc.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mmc/mxs-mmc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Freescale MXS MMC controller
+
+maintainers:
+  - Shawn Guo <shawn.guo@linaro.org>
+
+description: |
+  The Freescale MXS Synchronous Serial Ports (SSP) can act as a MMC controller
+  to support MMC, SD, and SDIO types of memory cards.
+
+  This file documents differences between the core properties in mmc.txt
+  and the properties used by the mxsmmc driver.
+
+allOf:
+  - $ref: "mmc-controller.yaml"
+
+properties:
+  compatible:
+    enum:
+      - fsl,imx23-mmc
+      - fsl,imx28-mmc
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  dmas:
+    maxItems: 1
+
+  dma-names:
+    const: rx-tx
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - dmas
+  - dma-names
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    mmc@80010000 {
+        compatible = "fsl,imx28-mmc";
+        reg = <0x80010000 2000>;
+        interrupts = <96>;
+        dmas = <&dma_apbh 0>;
+        dma-names = "rx-tx";
+        bus-width = <8>;
+    };