[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/drivers/media/pci/saa7134/saa7134.h b/drivers/media/pci/saa7134/saa7134.h
index 1a82dd0..c644c7d 100644
--- a/drivers/media/pci/saa7134/saa7134.h
+++ b/drivers/media/pci/saa7134/saa7134.h
@@ -588,6 +588,7 @@
 
 
 	/* video+ts+vbi capture */
+	void			   *alloc_ctx;
 	struct saa7134_dmaqueue    video_q;
 	struct vb2_queue           video_vbq;
 	struct saa7134_dmaqueue    vbi_q;