[media] soc_camera: fix expbuf support

- For vb1 drivers just return -ENOTTY.
- For vb2 drivers allow vb2_expbuf without there being a stream owner:
  the vb2_expbuf function will return the correct error message in that case.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/platform/soc_camera/soc_camera.c

@@ -470,13 +470,12 @@ static int soc_camera_expbuf(struct file *file, void *priv,
 	struct soc_camera_device *icd = file->private_data;
 	struct soc_camera_host *ici = to_soc_camera_host(icd->parent);
 
-	if (icd->streamer != file)
-		return -EBUSY;
-
 	/* videobuf2 only */
 	if (ici->ops->init_videobuf)
-		return -EINVAL;
-	else
+		return -ENOTTY;
+
+	if (icd->streamer && icd->streamer != file)
+		return -EBUSY;
 	return vb2_expbuf(&icd->vb2_vidq, p);
 }