Qualcomm QPNP Coincell - coincell battery charger devices

Required properties:
- compatible:      Must be "qcom,qpnp-coincell".
- reg:             Specifies the SPMI address and size for this coincell device.

Required structure:
- A qcom,qpnp-coincell node must be a child of an SPMI node that has specified
	the spmi-slave-container property.

Optional properties:
- qcom,rset-ohms:	Specifies the resistance of the current limiting
			resistor in ohms.  Four values are supported:
			800, 1200, 1700, and 2100.
- qcom,vset-millivolts:	Specifies the coincell charging voltage in millivolts.
			Four values are supported: 2500, 3000, 3100, and 3200.
- qcom,charge-enable:	Specifies if coincell charging should be enabled or not.
			0 = disable charging, 1 = enabled charging

If any of the optional properties are not specified, then the hardware default
values for the unspecified properties will be used instead.

Example:
	qcom,spmi@fc4c0000 {
		#address-cells = <1>;
		#size-cells = <0>;
		interrupt-controller;
		#interrupt-cells = <3>;

		qcom,pm8941@1 {
			spmi-slave-container;
			reg = <0x1>;
			#address-cells = <1>;
			#size-cells = <1>;

			qcom,coincell@2800 {
				compatible = "qcom,qpnp-coincell";
				reg = <0x2800 0x100>;
				qcom,rset-ohms = <800>;
				qcom,vset-millivolts = <3100>;
				qcom,charge-enable = <1>;
			};
		};
	};