media: staging: media: imx: fix inconsistent IS_ERR and PTR_ERR

Fix inconsistent IS_ERR and PTR_ERR in csi_link_validate.
The proper pointer to be passed as argument is sensor.

This issue was detected with the help of Coccinelle.
Reported-by: NJulia Lawall <julia.lawall@lip6.fr>
Signed-off-by: NGustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/staging/media/imx/imx-media-csi.c

@@ -989,7 +989,7 @@ static int csi_link_validate(struct v4l2_subdev *sd,
 	sensor = __imx_media_find_sensor(priv->md, &priv->sd.entity);
 	if (IS_ERR(sensor)) {
 		v4l2_err(&priv->sd, "no sensor attached\n");
-		return PTR_ERR(priv->sensor);
+		return PTR_ERR(sensor);
 	}
 
 	mutex_lock(&priv->lock);