perf lock: Add lock aggregation enum

Introduce the aggr_mode variable to prepare a later code change.

The default is LOCK_AGGR_ADDR which aggregates the result for the lock
instances.

When -t/--threads option is given, it'd be set to LOCK_AGGR_TASK.  The
LOCK_AGGR_CALLER is for the contention analysis and it'd aggregate the
stat by comparing the callstacks.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220725183124.368304-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>