media: pci: constify videobuf_queue_ops structures

videobuf_queue_ops are not supposed to change at runtime. All functions
working with videobuf_queue_ops provided by <media/videobuf-core.h> work
with const videobuf_queue_ops. So mark the non-const structs as const.
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NHans Verkuil <hansverk@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/pci/bt8xx/bttv-driver.c

@@ -1702,7 +1702,7 @@ static void buffer_release(struct videobuf_queue *q, struct videobuf_buffer *vb)
 	bttv_dma_free(q,fh->btv,buf);
 }
 
-static struct videobuf_queue_ops bttv_video_qops = {
+static const struct videobuf_queue_ops bttv_video_qops = {
 	.buf_setup    = buffer_setup,
 	.buf_prepare  = buffer_prepare,
 	.buf_queue    = buffer_queue,