dt-bindings: usb: bdc: Add Device Tree binding for Broadcom UDC driver

Broadcom USB Device Controller (BDC)

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Required properties:

- compatible: must be one of:

                "brcm,bdc-v0.16"

                "brcm,bdc"

- reg: the base register address and length

- interrupts: the interrupt line for this controller

Optional properties:

On Broadcom STB platforms, these properties are required:

- phys: phandle to one or two USB PHY blocks

        NOTE: Some SoC's have a single phy and some have

        USB 2.0 and USB 3.0 phys

- clocks: phandle to the functional clock of this block

Example:

        bdc@f0b02000 {

                compatible = "brcm,bdc-v0.16";

                reg = <0xf0b02000 0xfc4>;

                interrupts = <0x0 0x60 0x0>;

                phys = <&usbphy_0 0x0>;

                clocks = <&sw_usbd>;

        };