Drop obsolete fields from gRPC protocol

[PlagueCZ]

Summary

There are a few fields in dpdk.proto that are unused and no longer supported, namely VirtualFunction::domain/slot/bus/function.

Motivation

Since compatibility with older dpservice-cli is broken by the ironcore name-change, this is the perfect time to clean up.

Steps

• stop referencing those fields in dpservice-cli and dpservice-go (@vlorinc) #461
• change the protobuf definition file in dpservice