I resolved the issue. The MFT manual is wrong.
"SETTINGS_PORT1" is wrong.
"LINK_TYPE_P1" is the correct parameter name.
Also the value "3" (Auto) doesn't work in Windows, always recognized as IB and no "Port Protocol" tab showed.
So I had to set the value "2" (Ethernet) manually. After that my HCA was recognized as Ethernet card.
> mlxconfig -d mydevice set LINK_TYPE_P1=2 LINK_TYPE_P2=2