perf test: Fix test case perf evlist tests for s390x

perf test: Fix test case perf evlist tests for s390x

Perf test case 78: perf evlist tests fails on s390.

The failure is causes by grouping events cycles and instructions because
sampling does only support event cycles.  Change the group to software
events to fix this.

Output before:
  # ./perf test 78
  78: perf evlist tests              : FAILED!
  #

Output after:
  # ./perf test 78
  78: perf evlist tests              : Ok
  #

Fixes: db452961de939225 ("perf tests evlist: Add basic evlist test")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Jan Polensky <japo@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>