iommu/amd: Check if IOAPIC information is correct

When the IOAPIC information provided in the IVRS table is
not correct or not complete the system may not boot at all
when interrupt remapping is enabled. So check if this
information is correct and print out a firmware bug message
when it is not.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>