PM / devfreq: event: remove duplicate devfreq_event_get_drvdata()

there define two devfreq_event_get_drvdata() function in devfreq-event.h
when disable CONFIG_PM_DEVFREQ_EVENT, it will lead to build fail. So
remove devfreq_event_get_drvdata() function.

Fixes: f262f28c1470 ("PM / devfreq: event: Add devfreq_event class")
Cc: stable@vger.kernel.org
Signed-off-by: Lin Huang <hl@rock-chips.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>

include/linux/devfreq-event.h

@@ -148,11 +148,6 @@ static inline int devfreq_event_reset_event(struct devfreq_event_dev *edev)
 	return -EINVAL;
 }
 
-static inline void *devfreq_event_get_drvdata(struct devfreq_event_dev *edev)
-{
-	return ERR_PTR(-EINVAL);
-}
-
 static inline struct devfreq_event_dev *devfreq_event_get_edev_by_phandle(
 					struct device *dev, int index)
 {