AMD/IOMMU: consider hidden devices when flushing device I/O TLBs

AMD/IOMMU: consider hidden devices when flushing device I/O TLBs

Hidden devices are associated with DomXEN but usable by the
hardware domain. Hence they need flushing as well when all devices are
to have flushes invoked.

While there drop a redundant ATS-enabled check and constify the first
parameter of the involved function.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
master commit: 036432e8b27e1ef21e0f0204ba9b0e3972a031c2
master date: 2021-10-12 11:54:34 +0200