Trying to do this on the VMInstance side had problems because we can't
differentiate the 3 types of migration there. So, just update this in
the API side and hope everything goes well.
This introduces an edge bug: if a VM is using a macvtap SR-IOV device,
and then tries to migrate, and the migrate is aborted, the NIC lists
will be inconsistent.
When I revamp the VMInstance in the future, I should be able to correct
this, but for now we'll have to live with that edgecase.
Joshua Boniface
60e1da09dd