perf cs-etm: Only track threads instead of PID and TIDs

perf cs-etm: Only track threads instead of PID and TIDs

PIDs and TIDs are already contained within the thread struct, so to
avoid inconsistencies drop the extra members on the etm queue and only
use the thread struct.

At the same time stop using the 'unknown' thread. In a later commit
we will be making samples from multiple machines so it will be better
to use the idle thread of each machine rather than overlapping unknown
threads. Using the idle thread is also better because kernel addresses
with a previously unknown thread will now be assigned to a real kernel
thread.

Committer notes:

Resolved conflicts with:

  perf addr_location: Add init/exit/copy functions
  perf thread: Add accessor functions for thread
  perf thread: Remove notion of dead threads

That were present in tmp.perf-tools.next only.

Reviewed-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Acked-by: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20230612111403.100613-2-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>