iommu/amd: Allow non-IOMMUv2 devices in IOMMUv2 domains

Since devices with IOMMUv2 functionality might be in the
same group as devices without it, allow those devices in
IOMMUv2 domains too.
Otherwise attaching the group with the IOMMUv2 device to the
domain will fail.

Signed-off-by: Joerg Roedel <jroedel@suse.de>