hwmon: twl4030: Hwmon Driver for TWL4030 MADC

This driver exposes the sysfs nodes of the TWL4030 MADC module.
All the voltage channel values are expressed in terms of mV. Channel 13
and channel 14 are reserved. There are channels which represent
temperature and current the output is represented by celcius
and mA respectively.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>