thermal: core: move to_thermal_zone() macro to header file

Simply making this macro available to other thermal core
files.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
index 8994d2a..097abee 100644
--- a/drivers/thermal/thermal_core.h
+++ b/drivers/thermal/thermal_core.h
@@ -54,6 +54,9 @@
 	unsigned int weight; /* The weight of the cooling device */
 };
 
+#define to_thermal_zone(_dev) \
+	container_of(_dev, struct thermal_zone_device, device)
+
 int thermal_register_governor(struct thermal_governor *);
 void thermal_unregister_governor(struct thermal_governor *);
 void thermal_zone_device_rebind_exception(struct thermal_zone_device *,