PM / devfreq: Move private devfreq_update_stats() into devfreq

THe devfreq_update_stats() updates the 'struct devfreq_dev_status'
in order to get current status of devfreq device. It is only used
for the governors.

This patch moves the devfreq_update_stats() into devfreq directory.

Signed-off-by: Chanwoo Choi <[e-mail]>
Signed-off-by: MyungJoo Ham <[e-mail]>

drivers/devfreq/governor.h

···
 
 extern int devfreq_update_status(struct devfreq *devfreq, unsigned long freq);
 
+static inline int devfreq_update_stats(struct devfreq *df)
+{
+	return df->profile->get_dev_status(df->dev.parent, &df->last_status);
+}
 #endif /* _GOVERNOR_H */

include/linux/devfreq.h

···
 extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
 						int index);
 
-/**
- * devfreq_update_stats() - update the last_status pointer in struct devfreq
- * @df:		the devfreq instance whose status needs updating
- *
- *  Governors are recommended to use this function along with last_status,
- * which allows other entities to reuse the last_status without affecting
- * the values fetched later by governors.
- */
-static inline int devfreq_update_stats(struct devfreq *df)
-{
-	return df->profile->get_dev_status(df->dev.parent, &df->last_status);
-}
-
 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
 /**
  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq