LIBIPW_DATA_LEN
dev->max_mtu = LIBIPW_DATA_LEN;
priv->prom_net_dev->max_mtu = LIBIPW_DATA_LEN;
net_dev->max_mtu = LIBIPW_DATA_LEN;
#define LIBIPW_FRAME_LEN (LIBIPW_DATA_LEN + LIBIPW_HLEN)