iommu/amd: Introduce per PCI segment last_bdf

iommu/amd: Introduce per PCI segment last_bdf

Current code uses global "amd_iommu_last_bdf" to track the last bdf
supported by the system. This value is used for various memory
allocation, device data flushing, etc.

Introduce per PCI segment last_bdf which will be used to track last bdf
supported by the given PCI segment and use this value for all per
segment memory allocations. Eventually it will replace global
"amd_iommu_last_bdf".

Co-developed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20220706113825.25582-11-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>