perf auxtrace: Avoid redundant NULL check in auxtrace_mmap_params__set_idx()

Since commit eead8a011477 ("libperf threadmap: Don't segv for index 0 for the
NULL 'struct perf_thread_map' pointer"), perf_thread_map__pid() can
check for a NULL map and return -1 if idx is 0. Cleanup
auxtrace_mmap_params__set_idx() and remove the redundant NULL check.

No functional change intended.

Reviewed-by: Aditya Bodkhe <[e-mail]>
Reviewed-by: Adrian Hunter <[e-mail]>
Reviewed-by: Amit Machhiwal <[e-mail]>
Signed-off-by: Gautam Menghani <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/auxtrace.c

···
 
 	if (per_cpu) {
 		mp->cpu = perf_cpu_map__cpu(evlist->core.all_cpus, idx);
-		if (evlist->core.threads)
-			mp->tid = perf_thread_map__pid(evlist->core.threads, 0);
-		else
-			mp->tid = -1;
+		mp->tid = perf_thread_map__pid(evlist->core.threads, 0);
 	} else {
 		mp->cpu.cpu = -1;
 		mp->tid = perf_thread_map__pid(evlist->core.threads, idx);