iommu/vt-d: Check device list of domain in domain free path

iommu/vt-d: Check device list of domain in domain free path

When the IOMMU domain is about to be freed, it should not be set on any
device. Instead of silently dealing with some bug cases, it's better to
trigger a warning to report and fix any potential bugs at the first time.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220706025524.2904370-9-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>