perf pmu: Add #slots literal support for arm64

perf pmu: Add #slots literal support for arm64

The slots in each architecture may be different, so add #slots literal
to obtain the slots of different architectures, and the #slots can be
applied in the metric. Currently, The #slots just support for arm64,
and other architectures will return NAN.

On arm64, the value of slots is from the register PMMIR_EL1.SLOT, which
I can read in /sys/bus/event_source/device/armv8_pmuv3_*/caps/slots.
PMMIR_EL1.SLOT might read as zero if the PMU version is lower than
ID_AA64DFR0_EL1_PMUVer_V3P4 or the STALL_SLOT event is not implemented.

Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrew Kilroy <andrew.kilroy@arm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuai Xue <xueshuai@linux.alibaba.com>
Cc: Will Deacon <will@kernel.org>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: Zhuo Song <zhuo.song@linux.alibaba.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/1673940573-90503-2-git-send-email-renyu.zj@linux.alibaba.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>