Thermal: exynos: Add compatible string for exynos4412

Added compatible string for Exynos4412 SoC.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Amit Daniel Kachhap <amit.daniel@samsung.com>
Acked-by: Eduardo Valentin <eduardo.valentin@ti.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>