[media] vb2-dma-sg: add allocation context to dma-sg

Require that dma-sg also uses an allocation context. This is in preparation
for adding prepare/finish memops to sync the memory between DMA and CPU.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Pawel Osciak <pawel@osciak.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
diff --git a/include/media/videobuf2-dma-sg.h b/include/media/videobuf2-dma-sg.h
index 7b89852..14ce306 100644
--- a/include/media/videobuf2-dma-sg.h
+++ b/include/media/videobuf2-dma-sg.h
@@ -21,6 +21,9 @@
 	return (struct sg_table *)vb2_plane_cookie(vb, plane_no);
 }
 
+void *vb2_dma_sg_init_ctx(struct device *dev);
+void vb2_dma_sg_cleanup_ctx(void *alloc_ctx);
+
 extern const struct vb2_mem_ops vb2_dma_sg_memops;
 
 #endif