V4L/DVB (13549): v4l: Add video_device_node_name function

Many drivers access the device number (video_device::v4l2_devnode::num)
in order to print the video device node name. Add and use a helper
function to retrieve the video_device node name.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index 73c9867..9135f57 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -141,6 +141,11 @@
 	return video_get_drvdata(video_devdata(file));
 }
 
+static inline const char *video_device_node_name(struct video_device *vdev)
+{
+	return dev_name(&vdev->dev);
+}
+
 static inline int video_is_unregistered(struct video_device *vdev)
 {
 	return test_bit(V4L2_FL_UNREGISTERED, &vdev->flags);