thermal/drivers/mediatek/lvts_thermal: Remove .hw_tshut_temp

All the .hw_tshut_temp instances are initialized with the same value.
Let's remove those and use a common definition instead. If ever a
different value must be used in the future then an override parameter
could be added back.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20240402032729.2736685-4-nico@fluxnic.net