perf debug: Avoid setting 'quiet' to 'true' unnecessarily

When using --quiet to disable messages, we will set the 'quiet' variable
to 'true' first, then check that variable to decide whether we need to
call perf_quiet_option(), so no need to set 'quiet' to 'true' once more
in perf_quiet_option().

Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1520944274-37001-2-git-send-email-xieyisheng1@huawei.com


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