Add functionality to check the availability of the AMD IOMMU Performance
Counters and export this functionality to other core drivers, such as in this
case, a perf AMD IOMMU PMU.  This feature is not bound to any specific AMD
family/model other than the presence of the IOMMU with P-C enabled.

The AMD IOMMU P-C support static counting only at this time.
Signed-off-by: NSteven Kinney <steven.kinney@amd.com>
Signed-off-by: NSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1370466709-3212-2-git-send-email-suravee.suthikulpanit@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>