This is a virt-xml option to refresh a VM to use the latest machine
type version for the machine type it's currently using. Ex:
pseries-2.11 -> pseries
pc-q35-5.0 -> q35
This is useful for when qemu deprecates and removes the machine type
out from under you, or to pick up bug fixes.
Signed-off-by: Cole Robinson <crobinso@redhat.com>