perf inject: Cut AUX area samples

After decoding AUX area samples, the AUX area data is no longer needed
(having been replaced by synthesized events) so cut it out.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20191115124225.5247-9-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>