[media] uvcvideo: Add function to convert from queue to stream

Factorize the container_of() call into an inline function and update
callers.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/uvc/uvc_queue.c

@@ -36,6 +36,12 @@
  * the driver.
  */
 
+static inline struct uvc_streaming *
+uvc_queue_to_stream(struct uvc_video_queue *queue)
+{
+	return container_of(queue, struct uvc_streaming, queue);
+}
+
 /* -----------------------------------------------------------------------------
  * videobuf2 queue operations
  */
@@ -45,8 +51,7 @@ static int uvc_queue_setup(struct vb2_queue *vq, const struct v4l2_format *fmt,
 			   unsigned int sizes[], void *alloc_ctxs[])
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
-	struct uvc_streaming *stream =
-			container_of(queue, struct uvc_streaming, queue);
+	struct uvc_streaming *stream = uvc_queue_to_stream(queue);
 
 	/* Make sure the image size is large enough. */
 	if (fmt && fmt->fmt.pix.sizeimage < stream->ctrl.dwMaxVideoFrameSize)
@@ -109,8 +114,7 @@ static void uvc_buffer_queue(struct vb2_buffer *vb)
 static void uvc_buffer_finish(struct vb2_buffer *vb)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
-	struct uvc_streaming *stream =
-			container_of(queue, struct uvc_streaming, queue);
+	struct uvc_streaming *stream = uvc_queue_to_stream(queue);
 	struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);
 
 	if (vb->state == VB2_BUF_STATE_DONE)