Add NXP PF8100/PF8121A/PF8200 regulator driver.

PF8100/PF8121A/PF8200 is PMIC designed for highperformance
consumer applications. It features seven high efficiency buck,
four linear and one vsnvs regulators.

Tested in Engicam i.Core MX8M Mini SOM platform boards.
Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Link: https://lore.kernel.org/r/20201130112329.104614-2-jagan@amarulasolutions.comSigned-off-by: Mark Brown <broonie@kernel.org>