intel_iommu: Return page walk level even when the translation fails

intel_iommu: Return page walk level even when the translation fails

We will use this information in vtd_do_iommu_translate to populate the
IOMMUTLBEntry and indicate the correct page mask. This prevents ATS
devices from sending many useless translation requests when a megapage
or gigapage is not present.

Signed-off-by: Clement Mathieu--Drif <clement.mathieu--drif@eviden.com>
Message-Id: <20250628180226.133285-9-clement.mathieu--drif@eviden.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>