regulator: rtmv20: Adds support for Richtek RTMV20 load switch regulator

Add support for Richtek RTMV20 load switch regulator.

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Link: https://lore.kernel.org/r/1601277584-5526-1-git-send-email-u0084500@gmail.com


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