dt-bindings: trivial-devices: Add Injoinic power bank ICs

Some Injoinic power bank ICs feature an I2C interface which allows
monitoring and controlling the battery charger and boost converter.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>