NXP LPC32xx USB Clock Controller

Required properties:
- compatible: should be "nxp,lpc3220-usb-clk"
- reg:  should contain clock controller registers location and length
- #clock-cells: must be 1, the cell holds id of a clock provided by the
  USB clock controller

Examples:

	usb {
		#address-cells = <1>;
		#size-cells = <1>;
		compatible = "simple-bus";
		ranges = <0x0 0x31020000 0x00001000>;

		usbclk: clock-controller@f00 {
			compatible = "nxp,lpc3220-usb-clk";
			reg = <0xf00 0x100>;
			#clock-cells = <1>;
		};
	};
