hwmon: Add driver for EXYNOS4 TMU

This patch allows to read temperature
from TMU(Thermal Management Unit) of SAMSUNG EXYNOS4 series of SoC.

Signed-off-by: Donggeun Kim <dg77.kim@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>