AMD IOMMU requires IntCapXT registers to be setup in order to generate
its own interrupts (for Event Log, PPR Log, and GA Log) with 32-bit
APIC destination ID. Without this support, AMD IOMMU MSI interrupts
will not be routed correctly when booting the system in X2APIC mode.

Cc: Joerg Roedel <joro@8bytes.org>
Fixes: 90fcffd9 ('iommu/amd: Add support for IOMMU XT mode')
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>