Binding for EC Battery

Required properties:
- compatible: Should contain one of the following:
    * "rockchip,ec-battery"
- reg: integer, smbus address of the device.
- tvirtual_power: integer, test power, if battery is not exist;
- monitor_sec: integer, delay time of queue_delayed_work (s);


Optional properties:

Example:

ec_battery: ec_battery09 {
	compatible = "rockchip,ec-battery";
	reg = <0x76>;
	virtual_power = <0>;
	monitor_sec = <5>;
};