perf stat: Fix affinity memory leaks on error path

Missed cleanup when an error occurs.

Fixes: 49de1795 ("perf stat: No need to setup affinities when starting a workload")
Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20241001052327.7052-2-irogers@google.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>