perf sched: Free thread->priv using priv_destructor

perf sched: Free thread->priv using priv_destructor

In many perf sched subcommand saves priv data structure in the thread
but it forgot to free them.  As it's an opaque type with 'void *', it
needs to register that knows how to free the data.  In this case, just
regular 'free()' is fine.

Fixes: 04cb4fc4d40a5bf1 ("perf thread: Allow tools to register a thread->priv destructor")
Reviewed-by: Ian Rogers <irogers@google.com>
Tested-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250703014942.1369397-3-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>