perf/x86: Track pmu in per-CPU cpu_hw_events

Some platforms, e.g. Alder Lake, have hybrid architecture. In the same
package, there may be more than one type of CPU. The PMU capabilities
are different among different types of CPU. Perf will register a
dedicated PMU for each type of CPU.

Add a 'pmu' variable in the struct cpu_hw_events to track the dedicated
PMU of the current CPU.

Current x86_get_pmu() use the global 'pmu', which will be broken on a
hybrid platform. Modify it to apply the 'pmu' of the specific CPU.

Initialize the per-CPU 'pmu' variable with the global 'pmu'. There is
nothing changed for the non-hybrid platforms.

The is_x86_event() will be updated in the later patch ("perf/x86:
Register hybrid PMUs") for hybrid platforms. For the non-hybrid
platforms, nothing is changed here.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1618237865-33448-4-git-send-email-kan.liang@linux.intel.com