ipfilter: Remove dead code from "Virtualize ipfilter"

6d8a5eacae82 virtualized ipfilter for VNET. A few remnants of old
defunct code remained. Remove them. At the time it was not known if
6d8a5eacae82 would cause any issues. As it's been a number of years
since the conversion was done, it's certainly safe to remove the
dead code.

MFC after: 1 week