As explained in bsc#1219977, as soon as host-passthrough is not used as
CPU model, virtio devices just stop working, in a lot of VM
configurations.
This is not good, and a solution must be found upstream. In the
meanwhile, these reverts at least unbreak our package.
References: bsc#1219977
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>