regulator: rt6245: Add support for Richtek RT6245

Richtek RT6245 is a high-performance, synchronous step-down converter
that can deliver up to 14A output current with an input supply voltage
range of 4.5V to 17V.

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Link: https://lore.kernel.org/r/1622699844-19203-2-git-send-email-u0084500@gmail.com


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