dwmac4_prog_mtl_tx_algorithms() missing write operation

net: ethernet: stmmac: dwmac4_prog_mtl_tx_algorithms() missing write operation

The value of MTL_OPERATION_MODE is not written back

Signed-off-by: Cheng Han <hancheng2009@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>