thermal: Move struct thermal_attr to the private header

The structure belongs to the thermal core internals but it is exported
in the include/linux/thermal.h

For better self-encapsulation and less impact for the compilation if a
change is made on it. Move the structure in the thermal core internal
header file.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20200402142747.8307-2-daniel.lezcano@linaro.org

drivers/thermal/thermal_core.h

@@ -41,6 +41,11 @@ extern struct thermal_governor *__governor_thermal_table_end[];
 	     __governor < __governor_thermal_table_end;	\
 	     __governor++)
 
+struct thermal_attr {
+	struct device_attribute attr;
+	char name[THERMAL_NAME_LENGTH];
+};
+
 /*
  * This structure is used to describe the behavior of
  * a certain cooling device on a certain trip point

include/linux/thermal.h

@@ -35,6 +35,7 @@
 struct thermal_zone_device;
 struct thermal_cooling_device;
 struct thermal_instance;
+struct thermal_attr;
 
 enum thermal_device_mode {
 	THERMAL_DEVICE_DISABLED = 0,
@@ -119,11 +120,6 @@ struct thermal_cooling_device {
 	struct list_head node;
 };
 
-struct thermal_attr {
-	struct device_attribute attr;
-	char name[THERMAL_NAME_LENGTH];
-};
-
 /**
  * struct thermal_zone_device - structure for a thermal zone
  * @id:		unique id number for each thermal zone