NGBE_MAC_RX_FLOW_CTRL
mflcn = NGBE_READ_REG(hw, NGBE_MAC_RX_FLOW_CTRL);
NGBE_WRITE_REG(hw, NGBE_MAC_RX_FLOW_CTRL, mflcn);
NGBE_WRITE_REG_MASK(hw, NGBE_MAC_RX_FLOW_CTRL,