thermal: exynos: Make the zone handling use trip information

This code simplifies the zone handling to use the trip information passed
by the TMU driver and not the hardcoded macros. This also helps in adding
more zone support.

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>
Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>