[media] v4l2-ioctl: set readbuffers to 2 in g_parm

If g_parm is handled automatically, then set readbuffers to 2, which is the
minimum number of buffers videobuf uses.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/v4l2-ioctl.c

@@ -1680,6 +1680,7 @@ static long __video_do_ioctl(struct file *file,
 				break;
 
 			ret = 0;
+			p->parm.capture.readbuffers = 2;
 			if (ops->vidioc_g_std)
 				ret = ops->vidioc_g_std(file, fh, &std);
 			if (ret == 0)