regulator: lochnagar: Add support for the Cirrus Logic Lochnagar

Lochnagar is an evaluation and development board for Cirrus
Logic Smart CODEC and Amp devices. It allows the connection of
most Cirrus Logic devices on mini-cards, as well as allowing
connection of various application processor systems to provide a
full evaluation platform. This driver supports the board
controller chip on the Lochnagar board.

The Lochnagar board provides power supplies for the attached
CODEC/Amp device. Currently this driver supports the microphone
supplies and the digital core voltage for the attached
device. There are some additional supplies that will be
added in time but these supplies are sufficient for most
systems/use-cases.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>