perf tools: Only set filter for tracepoints events

perf_evlist__set_filter() tries to set filter to every evsel linked in
the evlist. However, since filters can only be applied to tracepoints,
checking type of evsel before calling perf_evsel__set_filter() would be
better.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1456479154-136027-6-git-send-email-wangnan0@huawei.com


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