Only call qemuMonitorGetMemoryStats for virtio memballoon
Only call qemuMonitorGetMemoryStats for virtio memballoon

There is nothing to get from the monitor for model='none'.

fabianfreyer/libvirt,fabianfreyer/libvirt,rlaager/libvirt,fabianfreyer/libvirt,eskultety/libvirt,zippy2/libvirt,VenkatDatta/libvirt,libvirt/libvirt,andreabolognani/libvirt,agx/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,jardasgit/libvirt,andreabolognani/libvirt,VenkatDatta/libvirt,crobinso/libvirt,libvirt/libvirt,rlaager/libvirt,libvirt/libvirt,nertpinx/libvirt,rlaager/libvirt,zippy2/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,crobinso/libvirt,VenkatDatta/libvirt,zippy2/libvirt,taget/libvirt,olafhering/libvirt,andreabolognani/libvirt,zippy2/libvirt,jardasgit/libvirt,taget/libvirt,andreabolognani/libvirt,eskultety/libvirt,andreabolognani/libvirt,nertpinx/libvirt,jardasgit/libvirt,jfehlig/libvirt,crobinso/libvirt,jardasgit/libvirt,taget/libvirt,olafhering/libvirt,VenkatDatta/libvirt,eskultety/libvirt,jardasgit/libvirt,datto/libvirt,rlaager/libvirt,crobinso/libvirt,olafhering/libvirt,rlaager/libvirt,agx/libvirt,nertpinx/libvirt,taget/libvirt,fabianfreyer/libvirt,eskultety/libvirt,nertpinx/libvirt,agx/libvirt,olafhering/libvirt,agx/libvirt,eskultety/libvirt,taget/libvirt,agx/libvirt,datto/libvirt,datto/libvirt,nertpinx/libvirt,jfehlig/libvirt,datto/libvirt,libvirt/libvirt,datto/libvirt