perf/smmuv3: Synthesize IIDR from CoreSight ID registers

perf/smmuv3: Synthesize IIDR from CoreSight ID registers

The SMMU_PMCG_IIDR register was not present in older revisions of the
Arm SMMUv3 spec. On Arm Ltd. implementations, the IIDR value consists of
fields from several PIDR registers, allowing us to present a
standardized identifier to userspace.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20211117144844.241072-4-jean-philippe@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>