selftests/ipc: Remove unused variables

Delete variables "msg" and "pid" that have never been used.

Link: https://lore.kernel.org/r/20241202045827.4704-1-zhangjiao2@cmss.chinamobile.com
Signed-off-by: zhang jiao <zhangjiao2@cmss.chinamobile.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/ipc/msgque.c

@@ -194,7 +194,7 @@ int fill_msgque(struct msgque_data *msgque)
 
 int main(int argc, char **argv)
 {
-	int msg, pid, err;
+	int err;
 	struct msgque_data msgque;
 
 	if (getuid() != 0)