Binding for Richtek rt9455 battery charger

Required properties:
- compatible:				it should contain one of the following:
					"richtek,rt9455".
- reg:					integer, i2c address of the device.
- interrupt-parent:			the phandle for the interrupt controller that
					services interrupts for this device.
- interrupts:				interrupt mapping for GPIO IRQ, it should be
					configured with IRQ_TYPE_LEVEL_LOW flag.
- richtek,output-charge-current:	integer, output current from the charger to the
					battery, in uA.
- richtek,end-of-charge-percentage:	integer, percent of the output charge current.
					When the current in constant-voltage phase drops
					below output_charge_current x end-of-charge-percentage,
					charge is terminated.
- richtek,battery-regulation-voltage:	integer, maximum battery voltage in uV.
- richtek,boost-output-voltage:		integer, maximum voltage provided to consumer
					devices, when the charger is in boost mode, in uV.

Optional properties:
- richtek,min-input-voltage-regulation: integer, input voltage level in uV, used to
					decrease voltage level when the over current
					of the input power source occurs.
					This prevents input voltage drop due to insufficient
					current provided by the power source.
					Default: 4500000 uV (4.5V)
- richtek,avg-input-current-regulation: integer, input current value in uA drained by the
					charger from the power source.
					Default: 500000 uA (500mA)

Example:

rt9455@22 {
	compatible = "richtek,rt9455";
	reg = <0x22>;

	interrupt-parent = <&gpio1>;
	interrupts = <0 IRQ_TYPE_LEVEL_LOW>;

	richtek,output-charge-current	    = <500000>;
	richtek,end-of-charge-percentage    = <10>;
	richtek,battery-regulation-voltage  = <4200000>;
	richtek,boost-output-voltage	    = <5050000>;

	richtek,min-input-voltage-regulation = <4500000>;
	richtek,avg-input-current-regulation = <500000>;
};
