commit 2c9195e9 upstream.

This did not work because devices are not put into the
pt_domain. Fix this.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
[bwh: Backported to 3.2: do not use iommu_dev_data::passthrough]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>