[media] media: blackfin: bfin_capture: set min_buffers_needed

this patch sets the min_buffers_needed field of the vb2 queue
so that the vb2 core will make sure start_streaming() callback
is called only when we have minimum buffers queued.
Signed-off-by: NLad, Prabhakar <prabhakar.csengg@gmail.com>
Tested-by: NScott Jiang <scott.jiang.linux@gmail.com>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/platform/blackfin/bfin_capture.c

@@ -986,6 +986,7 @@ static int bcap_probe(struct platform_device *pdev)
 	q->mem_ops = &vb2_dma_contig_memops;
 	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
 	q->lock = &bcap_dev->mutex;
+	q->min_buffers_needed = 1;
 
 	ret = vb2_queue_init(q);
 	if (ret)