perf/smmuv3: Support sysfs identifier file

mainline inclusion
from mainline-v5.10-rc3
commit 2c255223
category: feature
bugzilla: 175148
CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2c255223362e9747075320ba618bd5960b76e04f



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SMMU_PMCG_IIDR was added in the SMMUv3.3 spec.

For the perf tool to know the specific HW implementation, expose the
PMCG_IIDR contents only when set.

Signed-off-by: John Garry <john.garry@huawei.com>
Link: https://lore.kernel.org/r/1602149181-237415-5-git-send-email-john.garry@huawei.com


Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>