dt-bindings: usb: Add binding for TI USB8020B hub controller

The TI USB8020B is a USB 3.0 hub controller with 2 ports.

This initial version of the binding only describes USB related aspects
of the USB8020B, it does not cover the option of connecting the controller
as an i2c slave.
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Link: https://lore.kernel.org/r/20240227090228.22156-1-macpaul.lin@mediatek.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/ti,usb8020b.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/usb/ti,usb8020b.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI USB8020B USB 3.0 hub controller
+
+maintainers:
+  - Macpaul Lin <macpaul.lin@mediatek.com>
+
+allOf:
+  - $ref: usb-device.yaml#
+
+properties:
+  compatible:
+    enum:
+      - usb451,8025
+      - usb451,8027
+
+  reg: true
+
+  reset-gpios:
+    items:
+      - description: GPIO specifier for GRST# pin.
+
+  vdd-supply:
+    description:
+      VDD power supply to the hub
+
+  peer-hub:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      phandle to the peer hub on the controller.
+
+required:
+  - compatible
+  - reg
+  - peer-hub
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    usb {
+        dr_mode = "host";
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        /* 2.0 hub on port 1 */
+        hub_2_0: hub@1 {
+          compatible = "usb451,8027";
+          reg = <1>;
+          peer-hub = <&hub_3_0>;
+          reset-gpios = <&pio 7 GPIO_ACTIVE_HIGH>;
+          vdd-supply = <&usb_hub_fixed_3v3>;
+        };
+
+        /* 3.0 hub on port 2 */
+        hub_3_0: hub@2 {
+          compatible = "usb451,8025";
+          reg = <2>;
+          peer-hub = <&hub_2_0>;
+          reset-gpios = <&pio 7 GPIO_ACTIVE_HIGH>;
+          vdd-supply = <&usb_hub_fixed_3v3>;
+        };
+    };