V4L/DVB (13377): make struct videobuf_queue_ops constant

The videobuf_queue_ops function vector is not declared constant, but
there's no need for the videobuf layer to ever change it.  Make it const
so that videobuf users can make their operations const without warnings.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/include/media/videobuf-dma-sg.h b/include/media/videobuf-dma-sg.h
index dda47f0..53e72f7 100644
--- a/include/media/videobuf-dma-sg.h
+++ b/include/media/videobuf-dma-sg.h
@@ -103,7 +103,7 @@
 void *videobuf_sg_alloc(size_t size);
 
 void videobuf_queue_sg_init(struct videobuf_queue* q,
-			 struct videobuf_queue_ops *ops,
+			 const struct videobuf_queue_ops *ops,
 			 struct device *dev,
 			 spinlock_t *irqlock,
 			 enum v4l2_buf_type type,