V4L/DVB (6259): Fix vivi poll() method

Due to the replace of videobuf_read_one to videobuf_read_stream, poll()
method implementation is wrong. This fixes poll() implementation, making
read of /dev/video? to work again.

With this method, an USB driver can use video-buf, without needing to
request memory from the DMA-safe area.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/vivi.c b/drivers/media/video/vivi.c
index c14e2b3..01c9776 100644
--- a/drivers/media/video/vivi.c
+++ b/drivers/media/video/vivi.c
@@ -1122,9 +1122,8 @@
 	} else {
 		dprintk(1,"poll: read() interface\n");
 		/* read() capture */
-		buf = (struct vivi_buffer*)fh->vb_vidq.read_buf;
-		if (NULL == buf)
-			return POLLERR;
+		return videobuf_poll_stream(file, &fh->	vb_vidq,
+					    wait);
 	}
 	poll_wait(file, &buf->vb.done, wait);
 	if (buf->vb.state == STATE_DONE ||