perf svghelper: Avoid memory leak

On success path the sib_core and sib_thr values weren't being
freed. Detected by clang-tidy.

Signed-off-by: Ian Rogers <[e-mail]>
Acked-by: Namhyung Kim <[e-mail]>
Cc: Ravi Bangoria <[e-mail]>
Cc: Nick Desaulniers <[e-mail]>
Cc: Yang Jihong <[e-mail]>
Cc: Huacai Chen <[e-mail]>
Cc: Nathan Chancellor <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: [e-mail]
Cc: Ming Wang <[e-mail]>
Cc: Tom Rix <[e-mail]>
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/util/svghelper.c

···
 	int i, nr_cpus;
 	struct topology t;
 	char *sib_core, *sib_thr;
+	int ret = -1;
 
 	nr_cpus = min(env->nr_cpus_online, MAX_NR_CPUS);
 
···
 
 	scan_core_topology(topology_map, &t, nr_cpus);
 
-	return 0;
+	ret = 0;
 
 exit:
 	zfree(&t.sib_core);
 	zfree(&t.sib_thr);
 
-	return -1;
+	return ret;
 }