drivers/rtc/interface.c: return -EBUSY, not -EACCES when device is busy

If rtc->irq_task is non-NULL and task is NULL, they always
rtc_irq_set_freq(), whenever err is set to -EBUSY it will then immediately
be set to -EACCES, misleading the caller as to the underlying problem.

Signed-off-by: Chris Brand <[e-mail]>
Acked-by: Alessandro Zummo <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/rtc/interface.c

···
 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
 	if (rtc->irq_task != NULL && task == NULL)
 		err = -EBUSY;
-	if (rtc->irq_task != task)
+	else if (rtc->irq_task != task)
 		err = -EACCES;
-	if (!err) {
+	else {
 		if (rtc_update_hrtimer(rtc, enabled) < 0) {
 			spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 			cpu_relax();
···
 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
 	if (rtc->irq_task != NULL && task == NULL)
 		err = -EBUSY;
-	if (rtc->irq_task != task)
+	else if (rtc->irq_task != task)
 		err = -EACCES;
-	if (!err) {
+	else {
 		rtc->irq_freq = freq;
 		if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 			spin_unlock_irqrestore(&rtc->irq_task_lock, flags);