AMD IOMMU: fail if there is no southbridge IO-APIC

AMD IOMMU: fail if there is no southbridge IO-APIC

... but interrupt remapping is requested (with per-device remapping
tables). Without it, the timer interrupt is usually not working.

Inspired by Linux'es "iommu/amd: Work around wrong IOAPIC device-id in
IVRS table" (commit c2ff5cf5294bcbd7fa50f7d860e90a66db7e5059) by Joerg
Roedel <joerg.roedel@amd.com>.

Reported-by: Eric Houby <ehouby@yahoo.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Eric Houby <ehouby@yahoo.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>