Realtek rts39xx SoC USB EHCI controllers

Required properties:
  - compatible : should be "realtek,rts3903-ehci".
  - reg : should contain at least address and length of the standard EHCI
    register set for the device. Optional platform-dependent registers
    (debug-port or other) can be also specified here, but only after
    definition of standard EHCI registers.
  - interrupt-parent: Phandle of the parent interrupt controller
  - interrupts : one EHCI interrupt should be described here.
  - resets: List of phandle and reset specifier pairs, one pair for
  each reset signal that affects the device
  - reset-names: List of reset signal name strings sorted in the same order as
  the resets property

Example:
	usb_ehci: ehci@18100000 {
			compatible = "realtek,rts3903-ehci";
			reg = <0x18100000 0x1000>;
			interrupt-parent = <&cpuintc>;
			interrupts = <BSP_IRQ_USB>;
			resets = <&reset FORCE_RESET_U2HOST>;
			reset-names = "reset-usb-host";
	};
