On TLB invalidation commands, let's call registered
IOMMU notifiers. Those can only be UNMAP notifiers.
SMMUv3 does not support notification on MAP (VFIO).

This patch allows vhost use case where IOTLB API is notified
on each guest IOTLB invalidation.
Signed-off-by: NEric Auger <eric.auger@redhat.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1529653501-15358-5-git-send-email-eric.auger@redhat.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>