Spreadtrum SC2730 fast charger binding

Required properties:
 - compatible: Should be "sprd,sc2730-fast-chg".
 - reg: Address offset of charger register.
 - phys: Contains a phandle to the USB phy.
 - interrupt-parent: Specifies the phandle of the interrupt controller to which
 the IRQs from PMIC 2730 are delivered to.
 - interrupts: IRQ line info for sc2730.
 - sprd,input-voltage-microvolt: Specifies the input voltage for fast charging.

Example:

	sc2730-fchg@400 {
		compatible = "sprd,sc2730-fast-chg";
		reg = <0x400>;
		phys = <&ssphy>;
		interrupt-parent = <&sc2730_pmic>;
		interrupts = <5 IRQ_TYPE_LEVEL_HIGH>;
		sprd,input-voltage-microvolt = <9000000>;
	};
