dt-bindings: phy: Convert hisilicon,hi6220-usb-phy to DT schema

Convert the HiSilicon HI6220 USB PHY binding to DT schema format. It's a
straight forward conversion.

Signed-off-by: Rob Herring (Arm) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/phy/hisilicon,hi6220-usb-phy.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/hisilicon,hi6220-usb-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Hisilicon hi6220 USB PHY
+
+maintainers:
+  - Zhangfei Gao <[e-mail]>
+
+properties:
+  compatible:
+    const: hisilicon,hi6220-usb-phy
+
+  '#phy-cells':
+    const: 0
+
+  phy-supply:
+    description: PHY power supply.
+
+  hisilicon,peripheral-syscon:
+    description: Phandle to the system controller for PHY control.
+    $ref: /schemas/types.yaml#/definitions/phandle
+
+additionalProperties: false
+
+examples:
+  - |
+    usbphy {
+        compatible = "hisilicon,hi6220-usb-phy";
+        #phy-cells = <0>;
+        phy-supply = <&fixed_5v_hub>;
+        hisilicon,peripheral-syscon = <&sys_ctrl>;
+    };

Documentation/devicetree/bindings/phy/phy-hi6220-usb.txt

···
-Hisilicon hi6220 usb PHY
------------------------
-
-Required properties:
-- compatible: should be "hisilicon,hi6220-usb-phy"
-- #phy-cells: must be 0
-- hisilicon,peripheral-syscon: phandle of syscon used to control phy.
-Refer to phy/phy-bindings.txt for the generic PHY binding properties
-
-Example:
-	usb_phy: usbphy {
-		compatible = "hisilicon,hi6220-usb-phy";
-		#phy-cells = <0>;
-		phy-supply = <&fixed_5v_hub>;
-		hisilicon,peripheral-syscon = <&sys_ctrl>;
-	};