thermal: exynos: Add missing definations and code cleanup

This patch adds some extra register bitfield definations and cleans
up the code to prepare for moving register macros and definations inside
the TMU data section. In this code cleanup the TMU enable bit is correctly used
as bit0 and bit1 is taken care which is reserve bit.

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