Binding for sc8990 Li-Ion Charger

This driver will support the sc89890. There are
other ICs in the same family but those have not been tested.

Required properties:
- compatible: "sc,sc89890"
- reg: integer, i2c address of the device.
- interrupts: interrupt line;
- sc,battery-regulation-voltage: integer, maximum charging voltage (in uV);
- sc,charge-current: integer, maximum charging current (in uA);
- sc,termination-current: integer, charge will be terminated when current in
    constant-voltage phase drops below this value (in uA);
- sc,precharge-current: integer, maximum charge current during precharge
    phase (in uA);
- sc,minimum-sys-voltage: integer, when battery is charging and it is below
    minimum system voltage, the system will be regulated above
    minimum-sys-voltage setting (in uV);
- sc,boost-voltage: integer, VBUS voltage level in boost mode (in uV);
- sc,boost-max-current: integer, maximum allowed current draw in boost mode
    (in uA).

Example:

sc89890 {
	compatible = "sc,sc89890";
	reg = <0x6a>;

	interrupt-parent = <&gpio0>;
	interrupts = <RK_PD5 IRQ_TYPE_EDGE_FALLING>;

	sc,battery-regulation-voltage = <4200000>;
	sc,charge-current = <1000000>;
	sc,termination-current = <50000>;
	sc,precharge-current = <128000>;
	sc,minimum-sys-voltage = <3600000>;
	sc,boost-voltage = <5000000>;
	sc,boost-max-current = <1000000>;
	sc,ibatcomp-micro-ohms = <10>;
};