selftests/resctrl: Don't use ctrlc_handler() outside signal handling

selftests/resctrl: Don't use ctrlc_handler() outside signal handling

perf_event_open_llc_miss() calls ctrlc_handler() to cleanup if
perf_event_open() returns an error. Those cleanups, however, are not
the responsibility of perf_event_open_llc_miss() and it thus interferes
unnecessarily with the usual cleanup pattern. Worse yet,
ctrlc_handler() calls exit() in the end preventing the ordinary cleanup
done in the calling function from executing.

ctrlc_handler() should only be used as a signal handler, not during
normal error handling.

Remove call to ctrlc_handler() from perf_event_open_llc_miss(). As
unmounting resctrlfs and test cleanup are already handled properly
by error rollbacks in the calling functions, no other changes are
necessary.

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>