perf auxtrace: Add auxtrace_record__read_finish()

All ->read_finish() implementations are doing the same thing. Add a
helper function so that they can share the same implementation.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Wei Li <liwei391@huawei.com>
Link: http://lore.kernel.org/lkml/20200217082300.6301-1-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>