PCI: Mark AMD Raven iGPU ATS as broken in some platforms

Edgar reported [1] AMD Raven iGPU errors on several of his systems.  There
is no root cause.  Turn off ATS on these systems to avoid the issue.

[1] https://lore.kernel.org/linux-iommu/MWHPR10MB1310CDB6829DDCF5EA84A14689150@MWHPR10MB1310.namprd10.prod.outlook.com/

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/MWHPR10MB131082779A86BE4CCCF190B789CB0@MWHPR10MB1310.namprd10.prod.outlook.com
Reported-by: Edgar Merger <Edgar.Merger@emerson.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>