virt-host-validate-common: Print warning on missing IOMMU
virt-host-validate-common: Print warning on missing IOMMU

No only coverity warns about this, but it kind of makes sense
too. We have a test whether host supports IOMMU. Some platforms
don't have it, I know. But in that case we should print a message
that it's unknown whether platform has it or not.

Before:
  (no output)

After:
  QEMU: Checking for device assignment IOMMU support                         : WARN (Unknown if this platform has IOMMU support)

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

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