perf cs-etm: Fix endless record after being terminated

perf cs-etm: Fix endless record after being terminated

In __cmd_record(), when receiving SIGINT(ctrl + c), a 'done' flag will
be set and the event list will be disabled by evlist__disable() once.

While in auxtrace_record.read_finish(), the related events will be
enabled again, if they are continuous, the recording seems to be
endless.

If the cs_etm event is disabled, we don't enable it again here.

Note: This patch is NOT tested since i don't have such a machine with
coresight feature, but the code seems buggy same as arm-spe and
intel-pt.

Tester notes:

Thanks for looping, Adrian.  Applied this patch and tested with
CoreSight on juno board, it works well.

Signed-off-by: Wei Li <liwei391@huawei.com>
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Tan Xiaojun <tanxiaojun@huawei.com>
Cc: stable@vger.kernel.org # 5.4+
Link: http://lore.kernel.org/lkml/20200214132654.20395-4-adrian.hunter@intel.com
[ahunter: removed redundant 'else' after 'return']
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>