Documentation: devicetree: Add TI BQ25890 bindings

Binding for TI bq25890 Li-Ion Charger

Required properties:

- compatible: Should contain one of the following:

    * "ti,bq25890"

- 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);

- ti,precharge-current: integer, maximum charge current during precharge

    phase (in uA);

- ti,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);

- ti,boost-voltage: integer, VBUS voltage level in boost mode (in uV);

- ti,boost-max-current: integer, maximum allowed current draw in boost mode

    (in uA).

Optional properties:

- ti,boost-low-freq: boolean, if present boost mode frequency will be 500kHz,

    otherwise 1.5MHz;

- ti,use-ilim-pin: boolean, if present the ILIM resistor will be used and the

    input current will be the lower between the resistor setting and the IINLIM

    register setting;

- ti,thermal-regulation-threshold: integer, temperature above which the charge

    current is lowered, to avoid overheating (in degrees Celsius). If omitted,

    the default setting will be used (120 degrees);

Example:

bq25890 {

        compatible = "ti,bq25890";

        reg = <0x6a>;

        ti,battery-regulation-voltage = <4200000>;

        ti,charge-current = <1000000>;

        ti,termination-current = <50000>;

        ti,precharge-current = <128000>;

        ti,minimum-sys-voltage = <3600000>;

        ti,boost-voltage = <5000000>;

        ti,boost-max-current = <1000000>;

        ti,use-ilim-pin;

        ti,thermal-regulation-threshold = <120>;

};