BGX_SMUX_TX_APPEND
cfg = bgx_reg_read(bgx, lmacid, BGX_SMUX_TX_APPEND);
bgx_reg_modify(bgx, lmacid, BGX_SMUX_TX_APPEND, cfg);
bgx_reg_modify(bgx, lmacid, BGX_SMUX_TX_APPEND, SMU_TX_APPEND_FCS_D);