perf/amd/ibs: Make IBS a core pmu

perf/amd/ibs: Make IBS a core pmu

So far, only one pmu was allowed to be registered as core pmu and thus
IBS pmus were being registered as uncore. However, with the event context
rewrite, that limitation no longer exists and thus IBS pmus can also be
registered as core pmu. This makes IBS much more usable, for ex, user
will be able to do per-process precise monitoring on AMD:

Before patch:
  $ sudo perf record -e cycles:pp ls
  Error:
  Invalid event (cycles:pp) in per-thread mode, enable system wide with '-a'

After patch:
  $ sudo perf record -e cycles:pp ls
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.017 MB perf.data (33 samples) ]

Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lkml.kernel.org/r/20221115093904.1799-1-ravi.bangoria@amd.com