Device-Tree bindings for charger of Active-semi ACT8945A Multi-Function Device

Required properties:
 - compatible: "active-semi,act8945a-charger".
 - active-semi,chglev-gpios: charge current level phandle with args
   as described in ../gpio/gpio.txt.
 - active-semi,lbo-gpios: specify the low battery voltage detect phandle
   with args as as described in ../gpio/gpio.txt.
 - interrupts: <a b> where a is the interrupt number and b is a
   field that represents an encoding of the sense and level
   information for the interrupt.
 - interrupt-parent: the phandle for the interrupt controller that
   services interrupts for this device.

Optional properties:
 - active-semi,input-voltage-threshold-microvolt: unit: mV;
   Specifies the charger's input over-voltage threshold value;
   The value can be: 6600, 7000, 7500, 8000; default: 6600
 - active-semi,precondition-timeout: unit: minutes;
   Specifies the charger's PRECONDITION safety timer setting value;
   The value can be: 40, 60, 80, 0; If 0, it means to disable this timer;
   default: 40.
 - active-semi,total-timeout: unit: hours;
   Specifies the charger's total safety timer setting value;
   The value can be: 3, 4, 5, 0; If 0, it means to disable this timer;
   default: 3.

Example:
	pmic@5b {
		compatible = "active-semi,act8945a";
		reg = <0x5b>;
		status = "okay";

		charger {
			compatible = "active-semi,act8945a-charger";
			pinctrl-names = "default";
			pinctrl-0 = <&pinctrl_charger_chglev &pinctrl_charger_lbo &pinctrl_charger_irq>;
			interrupt-parent = <&pioA>;
			interrupts = <45 GPIO_ACTIVE_LOW>;

			active-semi,chglev-gpios = <&pioA 12 GPIO_ACTIVE_HIGH>;
			active-semi,lbo-gpios = <&pioA 72 GPIO_ACTIVE_LOW>;
			active-semi,input-voltage-threshold-microvolt = <6600>;
			active-semi,precondition-timeout = <40>;
			active-semi,total-timeout = <3>;
			status = "okay";
		};
	};