network: better validation of devices in hostdev network pool
network: better validation of devices in hostdev network pool

This adds a few validations to the devices listed for a hostdev network:

* devices must be listed by PCI address, not by netdev name

* listing a device by PCI address is valid only for hostdev networks, not
  for other types of network (e.g. macvtap passthrough).

* each device in a hostdev pool must be an SR-IOV VF

Resolves: https://bugzilla.redhat.com/1004676

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