thermal/core: Remove unneeded EXPORT_SYMBOLS

Different functions are exporting the symbols but are actually only
used by the thermal framework internals. Remove these EXPORT_SYMBOLS.

Cc: Alexandre Bailon <abailon@baylibre.com>
Cc: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linexp.org>
Link: https://lore.kernel.org/r/20220722200007.1839356-6-daniel.lezcano@linexp.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/thermal/thermal_helpers.c

@@ -39,7 +39,6 @@ int get_tz_trend(struct thermal_zone_device *tz, int trip)
 
 	return trend;
 }
-EXPORT_SYMBOL(get_tz_trend);
 
 struct thermal_instance *
 get_thermal_instance(struct thermal_zone_device *tz,
@@ -228,7 +227,6 @@ void thermal_cdev_update(struct thermal_cooling_device *cdev)
 	}
 	mutex_unlock(&cdev->lock);
 }
-EXPORT_SYMBOL(thermal_cdev_update);
 
 /**
  * thermal_zone_get_slope - return the slope attribute of the thermal zone