nbpf_xfer_size
chan->slave_dst_width = nbpf_xfer_size(chan->nbpf,
chan->slave_dst_burst = nbpf_xfer_size(chan->nbpf,
chan->slave_src_width = nbpf_xfer_size(chan->nbpf,
chan->slave_src_burst = nbpf_xfer_size(chan->nbpf,