thermal/core: Add missing EXPORT_SYMBOL_GPL

The function thermal_zone_device_register_with_trips() is not exported
for modules.

Add the missing EXPORT_SYMBOL_GPL().

Fixes: fae11de5

 ("thermal/core: Add thermal_trip in thermal_zone")
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20220810100731.749317-1-daniel.lezcano@linaro.org