Hey Pilu1978,
Your command is failing because you need to specify the dvportgroup-id and you are specifying the port-id from a PortGroup. However I could not find a way of getting dvportgroup-id without any interface connected to it.
Of course there are a lot of places to get that information such as vCenter MOB, vCenter API, using vRealize Orchestrator, using external tools and I think even using PowerCLI. Try to go over those solutions to see if you can get it or what you can do to easily get it is to create a VMK interface manually from the UI and after you create it, run the command esxcfg-vswitch -l and record the dvportgroup-id