perf test: No need for setting attr.sample_freq on the RECORD test

perf test: No need for setting attr.sample_freq on the RECORD test

We're not looking at PERF_RECORD_SAMPLE entries and now by default we
use PERF_COUNT_SW_DUMMY, so just remove that setting.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-cly7cnotktv5rqao13pkorem@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>