AMD/IOMMU: pull ATS disabling earlier

AMD/IOMMU: pull ATS disabling earlier

Disabling should be done in the opposite order of enabling: ATS wants to
be turned off before adjusting the DTE, just like it gets enabled only
after the DTE was suitably prepared. Note that we want ATS to be
disabled as soon as any of the DTEs involved in the handling of a device
(including phantom devices) gets adjusted respectively. For this reason
the "devfn == pdev->devfn" of the original conditional gets dropped.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>