thermal: exynos: Add support to access common register for multistance

This patch adds support to parse one more common set of TMU register. First
set of register belongs to each instance of TMU and second set belongs to
common TMU registers.

Acked-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Acked-by: Eduardo Valentin <eduardo.valentin@ti.com>
Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>