dt-bindings: power: supply: ab8500_fg: Add line impedance

To improve the inner resistance measurement of the battery we need
to account for the line impedance of the connector to the battery.

Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Documentation/devicetree/bindings/power/supply/stericsson,ab8500-fg.yaml

@@ -25,6 +25,11 @@ properties:
     $ref: /schemas/types.yaml#/definitions/phandle
     deprecated: true
 
+  line-impedance-micro-ohms:
+    description: The line impedance between the battery and the
+      AB8500 inputs, to compensate for this when determining internal
+      resistance.
+
   interrupts:
     maxItems: 5