hwmon: lochnagar: Add Lochnagar 2 hardware monitoring driver

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 adds support for the hardware monitoring features of
the Lochnagar 2 to the hwmon API. Monitoring is provided for
the board voltages, currents and temperature supported by the
board controller chip.

Signed-off-by: Lucas Tanure <tanureal@opensource.cirrus.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>