amd/iommu: skip host bridge devices when updating IOMMU page tables

amd/iommu: skip host bridge devices when updating IOMMU page tables

Host bridges are not behind an IOMMU, and are already special cased and
skipped in amd_iommu_add_device. Apply the same special casing when
updating page tables.

This is required or else update_paging_mode will fail and return an
error to the caller (amd_iommu_{un}map_page) which will destroy the
domain.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Brian Woods <brian.woods@amd.com>