Xilinx SuperSpeed DWC3 USB SoC controller

Required properties:
- compatible:	May contain "xlnx,zynqmp-dwc3" or "xlnx,versal-dwc3"
- reg:		Base address and length of the register control block
- clocks:	A list of phandles for the clocks listed in clock-names
- clock-names:	Should contain the following:
  "bus_clk"	 Master/Core clock, have to be >= 125 MHz for SS
		 operation and >= 60MHz for HS operation

  "ref_clk"	 Clock source to core during PHY power down
- resets:	A list of phandles for resets listed in reset-names
- reset-names:
  "usb_crst"	 USB core reset
  "usb_hibrst"	 USB hibernation reset
  "usb_apbrst"	 USB APB reset

Required child node:
A child node must exist to represent the core DWC3 IP block. The name of
the node is not important. The content of the node is defined in dwc3.txt.

Optional properties for snps,dwc3:
- dma-coherent:	Enable this flag if CCI is enabled in design. Adding this
		flag configures Global SoC bus Configuration Register and
		Xilinx USB 3.0 IP - USB coherency register to enable CCI.
- interrupt-names: Should contain the following:
  "dwc_usb3"	USB gadget mode interrupts
  "otg"		USB OTG mode interrupts
  "hiber"	USB hibernation interrupts

Example device node:

		usb@0 {
			#address-cells = <0x2>;
			#size-cells = <0x1>;
			compatible = "xlnx,zynqmp-dwc3";
			reg = <0x0 0xff9d0000 0x0 0x100>;
			clock-names = "bus_clk", "ref_clk";
			clocks = <&clk125>, <&clk125>;
			resets = <&zynqmp_reset ZYNQMP_RESET_USB1_CORERESET>,
				 <&zynqmp_reset ZYNQMP_RESET_USB1_HIBERRESET>,
				 <&zynqmp_reset ZYNQMP_RESET_USB1_APB>;
			reset-names = "usb_crst", "usb_hibrst", "usb_apbrst";
			ranges;

			dwc3@fe200000 {
				compatible = "snps,dwc3";
				reg = <0x0 0xfe200000 0x40000>;
				interrupt-names = "dwc_usb3", "otg", "hiber";
				interrupts = <0 65 4>, <0 69 4>, <0 75 4>;
				phys = <&psgtr 2 PHY_TYPE_USB3 0 2>;
				phy-names = "usb3-phy";
				dr_mode = "host";
				dma-coherent;
			};
		};