media: add 'index' to struct media_v2_pad

The v2 pad structure never exposed the pad index, which made it impossible
to call the MEDIA_IOC_SETUP_LINK ioctl, which needs that information.

It is really trivial to just expose this information, so implement this.

Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 47bb225..047d383 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -331,6 +331,7 @@ static long media_device_get_topology(struct media_device *mdev, void *arg)
 		kpad.id = pad->graph_obj.id;
 		kpad.entity_id = pad->entity->graph_obj.id;
 		kpad.flags = pad->flags;
+		kpad.index = pad->index;
 
 		if (copy_to_user(upad, &kpad, sizeof(kpad)))
 			ret = -EFAULT;