dt-bindings: power: ingenic,battery: add new compatibles

This binding can support Ingenic JZ4725B and JZ4770 SoCs, as they are
compatible with Ingenic JZ4740 battery.

Introduce the following compatible property combinations:
 compatible = "ingenic,jz4725b-battery", "ingenic,jz4740-battery",
 compatible = "ingenic,jz4770-battery", "ingenic,jz4740-battery"

Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>