regulator: regulator driver for Palmas series chips

Palmas has both Switched Mode (SMPS) and Linear (LDO) regulators in it.
This regulator driver allows software control of these regulators.

The regulators available on Palmas series chips vary depending on the muxing.
This is handled automatically in the driver by reading the mux info from OTP.
Signed-off-by: Graeme Gregory <gg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>