regulator: dt-bindings: fcs,fan53555: Add support for RK860X

Add compatibles to support Rockchip RK860X regulators.

RK8600/RK8601 are pretty similar to the FAN53555 regulators, while
RK8602/RK8603 are a bit different, having a wider voltage selection
range.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230406194158.963352-2-cristian.ciocaltea@collabora.com


Signed-off-by: Mark Brown <broonie@kernel.org>