[media] v4l2: add v4l2_prio_state to v4l2_device and video_device

Integrate the v4l2_prio_state into the core, ready for use.

One struct v4l2_prio_state is added to v4l2_device and a pointer
to a prio state is added to video_device.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 65d546f..6b1ef85d 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -573,6 +573,12 @@
 			vdev->parent = vdev->v4l2_dev->dev;
 		if (vdev->ctrl_handler == NULL)
 			vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
+		/* If the prio state pointer is NULL, and if the driver doesn't
+		   handle priorities itself, then use the v4l2_device prio
+		   state. */
+		if (vdev->prio == NULL && vdev->ioctl_ops &&
+				vdev->ioctl_ops->vidioc_s_priority == NULL)
+			vdev->prio = &vdev->v4l2_dev->prio;
 	}
 
 	/* Part 2: find a free minor, device node number and device index. */