perf bpf-loader: use PTR_ERR_OR_ZERO inetead of return code

Use PTR_ERR_OR_ZERO() in bpf__setup_stdout() return code instead of open
coded equivalent.

Signed-off-by: Ding Xiang <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/bpf-loader.c

···
 int bpf__setup_stdout(struct perf_evlist *evlist)
 {
 	struct perf_evsel *evsel = bpf__setup_output_event(evlist, "__bpf_stdout__");
-	return IS_ERR(evsel) ? PTR_ERR(evsel) : 0;
+	return PTR_ERR_OR_ZERO(evsel);
 }
 
 #define ERRNO_OFFSET(e)		((e) - __BPF_LOADER_ERRNO__START)