iommu: Use dev_iommu_ops() for probe_finalize

The ->probe_finalize hook only runs after ->probe_device succeeds,
so we can move that over to the new dev_iommu_ops() as well.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/5fe4b0ce22f676f435d332f2b2828dc7ef848a19.1655822151.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>