Thermal: List thermal_instance in thermal_cooling_device.

List thermal_instance in thermal_cooling_device so that
cooling device can know the cooling state requirement
of all the thermal instances.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Eduardo Valentin <eduardo.valentin@ti.com>
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index cb0b0e3..9ae378a 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -94,6 +94,7 @@
 	struct device device;
 	void *devdata;
 	const struct thermal_cooling_device_ops *ops;
+	struct list_head thermal_instances;
 	struct list_head node;
 };