fix previous commit

Author: Simon Morlat

src/videofilters/msv4l2.c

@@ -471,6 +471,7 @@ static mblk_t *v4l2_dequeue_ready_buffer(V4l2State *s, int poll_timeout_ms){
 switch (errno) {
 case EAGAIN:
 ms_warning("VIDIOC_DQBUF failed with EAGAIN, this is a driver bug !");
+usleep(20000);
 case EIO:
 /* Could ignore EIO, see spec. */
 break;