dt-bindings: power/supply: Add ltc4162-l-charger

Add support for the LTC4162-L Li-Ion battery charger. The driver allows
reading back telemetry and to set some charging options like the input
current limit.

This adds the devicetree bindings.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>