Binding for TI bq24257 Li-Ion Charger

Required properties:
- compatible: Should contain one of the following:
 * "ti,bq24257"
- reg:			   integer, i2c address of the device.
- ti,battery-regulation-voltage: integer, maximum charging voltage in uV.
- ti,charge-current:	   integer, maximum charging current in uA.
- ti,termination-current:  integer, charge will be terminated when current in
			   constant-voltage phase drops below this value (in uA).

Example:

bq24257 {
	compatible = "ti,bq24257";
	reg = <0x6a>;

	ti,battery-regulation-voltage = <4200000>;
	ti,charge-current = <1000000>;
	ti,termination-current = <50000>;
};