amd/iommu: Fix Guest Virtual APIC Log Tail Address Register

This register should have been programmed with the physical address
of the memory location containing the shadow tail pointer for
the guest virtual APIC log instead of the base address.

Fixes: 8bda0cfb  ('iommu/amd: Detect and initialize guest vAPIC log')
Signed-off-by: Filippo Sironi <sironi@amazon.de>
Signed-off-by: Wei Wang <wawei@amazon.de>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>