ARM: HWMON: S3C24XX series ADC driver

Add support for the ADC controller on the S3C series of processors to
drivers/hwmon for use with hardware monitoring systems.

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>