iommu/vt-d: Remove DEFER_DEVICE_DOMAIN_INFO

Allocate and set the per-device iommu private data during iommu device
probe. This makes the per-device iommu private data always available
during iommu_probe_device() and iommu_release_device(). With this changed,
the dummy DEFER_DEVICE_DOMAIN_INFO pointer could be removed. The wrappers
for getting the private data and domain are also cleaned.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20220214025704.3184654-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20220301020159.633356-6-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>