Fix format-security warnings by using proper format strings when
passing message variables to ksft_exit_fail_msg(),
ksft_test_result_pass(), and ksft_test_result_skip() function.

This prevents potential security issues and eliminates compiler warnings
when building with -Wformat-security.

Signed-off-by: Nai-Chen Cheng <bleach1827@gmail.com>
---

Changes in v2:
- Fix typo in subject: "selftest" -> "selftests"
- Retested compilation and functionality
- Link to v1: https://lore.kernel.org/all/20250717120606.45115-1-bleach1827@gmail.com/

---
diff --git a/tools/testing/selftests/futex/functional/futex_priv_hash.c b/tools/testing/selftests/futex/functional/futex_priv_hash.c
index 24a92dc94eb8..19651087c4de 100644
--- a/tools/testing/selftests/futex/functional/futex_priv_hash.c
+++ b/tools/testing/selftests/futex/functional/futex_priv_hash.c
@@ -184,10 +184,10 @@ int main(int argc, char *argv[])
 	futex_slots1 = futex_hash_slots_get();
 	if (futex_slots1 <= 0) {
 		ksft_print_msg("Current hash buckets: %d\n", futex_slots1);
-		ksft_exit_fail_msg(test_msg_auto_create);
+		ksft_exit_fail_msg("%s", test_msg_auto_create);
 	}
 
-	ksft_test_result_pass(test_msg_auto_create);
+	ksft_test_result_pass("%s", test_msg_auto_create);
 
 	online_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 	ret = pthread_barrier_init(&barrier_main, NULL, MAX_THREADS + 1);
@@ -212,11 +212,11 @@ int main(int argc, char *argv[])
 		if (futex_slotsn < 0 || futex_slots1 == futex_slotsn) {
 			ksft_print_msg("Expected increase of hash buckets but got: %d -> %d\n",
 				       futex_slots1, futex_slotsn);
-			ksft_exit_fail_msg(test_msg_auto_inc);
+			ksft_exit_fail_msg("%s", test_msg_auto_inc);
 		}
-		ksft_test_result_pass(test_msg_auto_inc);
+		ksft_test_result_pass("%s", test_msg_auto_inc);
 	} else {
-		ksft_test_result_skip(test_msg_auto_inc);
+		ksft_test_result_skip("%s", test_msg_auto_inc);
 	}
 	ret = pthread_mutex_unlock(&global_lock);
 
-- 
2.43.0