regulator: rtq2208: Add Richtek RTQ2208 SubPMIC driver

Add support for the RTQ2208 SubPMIC
This ic integrates with configurable, synchrnous buck converters and two ldos.

Signed-off-by: Alina Yu <alina_yu@richtek.com>
Link: https://lore.kernel.org/r/1691389687-31211-3-git-send-email-alina_yu@richtek.com


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