V4L/DVB (8613): v4l: move BKL down to the driver level.

The BKL is now moved from the video_open function in v4l2-dev.c to the
various drivers. It seems about a third of the drivers already has a
lock of some sort protecting the open(), another third uses
video_exclusive_open (yuck!) and the last third required adding the
BKL in their open function.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/stk-webcam.c b/drivers/media/video/stk-webcam.c
index ad36af3..6b1ef5d 100644
--- a/drivers/media/video/stk-webcam.c
+++ b/drivers/media/video/stk-webcam.c
@@ -689,11 +689,15 @@
 	vdev = video_devdata(fp);
 	dev = vdev_to_camera(vdev);
 
-	if (dev == NULL || !is_present(dev))
+	lock_kernel();
+	if (dev == NULL || !is_present(dev)) {
+		unlock_kernel();
 		return -ENXIO;
+	}
 	fp->private_data = vdev;
 	kref_get(&dev->kref);
 	usb_autopm_get_interface(dev->interface);
+	unlock_kernel();
 
 	return 0;
 }