[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/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index 9193703..3700127 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -89,6 +89,9 @@
 	/* Control handler associated with this device node. May be NULL. */
 	struct v4l2_ctrl_handler *ctrl_handler;
 
+	/* Priority state. If NULL, then v4l2_dev->prio will be used. */
+	struct v4l2_prio_state *prio;
+
 	/* device info */
 	char name[32];
 	int vfl_type;