dt-bindings: phy: nuvoton,ma35-usb2-phy: add new bindings

Add dt-bindings for USB2 PHY found on the Nuvoton MA35 SoC.
Signed-off-by: Hui-Ping Chen <hpchen0nvt@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240805030356.14565-2-hpchen0nvt@gmail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/nuvoton,ma35d1-usb2-phy.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/nuvoton,ma35d1-usb2-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nuvoton MA35D1 USB2 phy
+
+maintainers:
+  - Hui-Ping Chen <hpchen0nvt@gmail.com>
+
+properties:
+  compatible:
+    enum:
+      - nuvoton,ma35d1-usb2-phy
+
+  "#phy-cells":
+    const: 0
+
+  clocks:
+    maxItems: 1
+
+  nuvoton,sys:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      phandle to syscon for checking the PHY clock status.
+
+required:
+  - compatible
+  - "#phy-cells"
+  - clocks
+  - nuvoton,sys
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/nuvoton,ma35d1-clk.h>
+
+    usb_phy: usb-phy {
+        compatible = "nuvoton,ma35d1-usb2-phy";
+        clocks = <&clk USBD_GATE>;
+        nuvoton,sys = <&sys>;
+        #phy-cells = <0>;
+    };