dt-bindings: power: supply: max17040: Add maxim,rcomp

To compensate for the battery chemistry and operating conditions the
chips support a compensation value. Specify one or two byte compensation
via the maxim,rcomp byte array.

Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>