thermal: mtk: Cleanup unused defines

The mtk_thermal has some defiens which are never used within the driver.
This patch delets them.

Signed-off-by: Matthias Brugger <mbrugger@suse.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>