power: supply: bq25890: document IBAT compensation DT properties

Document new properties for IBAT compensation feature.
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

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

@@ -33,6 +33,10 @@ Optional properties:
 - 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);
+- ti,ibatcomp-micro-ohms: integer, value of a resistor in series with
+    the battery;
+- ti,ibatcomp-clamp-microvolt: integer, maximum charging voltage adjustment due
+    to expected voltage drop on in-series resistor;
 
 Example: