usb: appledisplay: Remove unnecessary spinlock

The spinlock was inside the urb completion function which is only
called once per display and is then resubmitted from this function.
There was no other place where this lock was used.

Signed-off-by: Alexander Theissen <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/misc/appledisplay.c

···
 
 	struct delayed_work work;
 	int button_pressed;
-	spinlock_t lock;
 	struct mutex sysfslock;		/* concurrent read and write */
 };
 
···
 {
 	struct appledisplay *pdata = urb->context;
 	struct device *dev = &pdata->udev->dev;
-	unsigned long flags;
 	int status = urb->status;
 	int retval;
 
···
 		goto exit;
 	}
 
-	spin_lock_irqsave(&pdata->lock, flags);
-
 	switch(pdata->urbdata[1]) {
 	case ACD_BTN_BRIGHT_UP:
 	case ACD_BTN_BRIGHT_DOWN:
···
 		pdata->button_pressed = 0;
 		break;
 	}
-
-	spin_unlock_irqrestore(&pdata->lock, flags);
 
 exit:
 	retval = usb_submit_urb(pdata->urb, GFP_ATOMIC);
···
 
 	pdata->udev = udev;
 
-	spin_lock_init(&pdata->lock);
 	INIT_DELAYED_WORK(&pdata->work, appledisplay_work);
 	mutex_init(&pdata->sysfslock);