dt-bindings: power: supply: New bindings for ltc3651-charger

This adds the devicetree bindings documentation for the LTC3651 battery charger.

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