[media] omap3isp: consistently use v4l2_dev var in complete notifier

The isp_subdev_notifier_complete() complete callback defines a struct
v4l2_device *v4l2_dev to avoid needing two level of indirections to
access the V4L2 subdevs but the var is not always used when possible
as when calling v4l2_device_register_subdev_nodes().

So change that to consistently use the defined v4l2_dev pointer var.
Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/platform/omap3isp/isp.c

@@ -2365,7 +2365,7 @@ static int isp_subdev_notifier_complete(struct v4l2_async_notifier *async)
 		}
 	}
 
-	return v4l2_device_register_subdev_nodes(&isp->v4l2_dev);
+	return v4l2_device_register_subdev_nodes(v4l2_dev);
 }
 
 /*