iommu/amd: Convert to use rlookup_amd_iommu helper function

Use rlookup_amd_iommu() helper function which will give per PCI
segment rlookup_table.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20220706113825.25582-16-vasant.hegde@amd.com


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