xn ethernet issues as DOMU under NetBSD DOM0

[Miguel C]

This was reported by me and others a few times its was actually fixed in
some 10.0 (current build at the time) but we could never track it, however
it always seemed related to tso, netbsd backhend (as I was told back then)
doesn't support at least tso, and In fact I had the same issue with Windwos
Guests but the PV drivers dev fixed it (and it was indeed related to this)

Anway I am just typing as I remember but I the were PRs about this I can't
look them up right now but I could later in the week or maybe someone else
can...