tests/events: s/printf/puts/ where applicable

tests/events/main.c

@@ -71,7 +71,7 @@ static void timed_callback(void *arg)
     uint32_t now = xtimer_now_usec();
     assert((now - before >= 100000LU));
     printf("triggered timed callback with arg 0x%08x after %" PRIu32 "us\n", (unsigned)arg, now - before);
-    printf("[SUCCESS]\n");
+    puts("[SUCCESS]");
 }
 
 static void forbidden_callback(void *arg)
@@ -98,12 +98,12 @@ int main(void)
     printf("canceling 0x%08x\n", (unsigned)&event2);
     event_cancel(&queue, &event2);
 
-    printf("posting custom event\n");
+    puts("posting custom event");
     event_post(&queue, (event_t *)&custom_event);
 
     event_timeout_t event_timeout;
 
-    printf("posting timed callback with timeout 1sec\n");
+    puts("posting timed callback with timeout 1sec");
     event_timeout_init(&event_timeout, &queue, (event_t *)&event_callback);
     before = xtimer_now_usec();
     event_timeout_set(&event_timeout, 100000LU);
@@ -116,7 +116,7 @@ int main(void)
     event_timeout_set(&event_timeout_canceled, 500 * US_PER_MS);
     event_timeout_clear(&event_timeout_canceled);
 
-    printf("launching event queue\n");
+    puts("launching event queue");
     event_loop(&queue);
 
     return 0;