regulator: mt6311: Add support for mt6311 regulator

Add regulator support for mt6311.
It has 2 regulaotrs - Buck and LDO, provide the related buck/ldo voltage
data to the driver, and creates the regulator_desc table. Supported
operations for Buck are enabled/disabled and voltage change, only
enabled/disabled for LDO.

Signed-off-by: Henry Chen <henryc.chen@mediatek.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>