thermal: exynos: do not use trips structure directly in ->tmu_initialize

Use ->get_trip_[temp,hyst] methods instead of using trips structure
directly in all ->tmu_initialize method implementations.

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>