vtd/iommu: permit group devices to passthrough in relaxed mode

vtd/iommu: permit group devices to passthrough in relaxed mode

Currently we don't allow passing through any group devices which are
sharing same RMRR entry since it would break security among VMs. And
indeed, we expect we can figure out a better way to handle this kind
of case completely.

But before the group assignment gets implemented, we might make this
permission dependent on our RMRR policy. So, now it would be allowed
in the relaxed mode.

Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>