dt-bindings: power: supply: bq25890: Document required interrupt

The driver requires interrupts (fails probe if it is not provided) so
document this requirement in bindings.

Fixes: 4aeae9cb ("power_supply: Add support for TI BQ25890 charger chip")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Documentation/devicetree/bindings/power/supply/bq25890.txt

@@ -10,6 +10,7 @@ Required properties:
     * "ti,bq25895"
     * "ti,bq25896"
 - reg: integer, i2c address of the device.
+- interrupts: interrupt line;
 - 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
@@ -39,6 +40,9 @@ bq25890 {
 	compatible = "ti,bq25890";
 	reg = <0x6a>;
 
+	interrupt-parent = <&gpio1>;
+	interrupts = <16 IRQ_TYPE_EDGE_FALLING>;
+
 	ti,battery-regulation-voltage = <4200000>;
 	ti,charge-current = <1000000>;
 	ti,termination-current = <50000>;