Fix deprecated usage of lock_memory API (#1970) (#1971)

(cherry picked from commit 52a2ffd)

Co-authored-by: Sudip Roy <[email protected]>

controller_manager/src/ros2_control_node.cpp

@@ -58,10 +58,13 @@ int main(int argc, char ** argv)
   }
   const bool has_realtime = realtime_tools::has_realtime_kernel();
   const bool lock_memory = cm->get_parameter_or<bool>("lock_memory", has_realtime);
-  std::string message;
-  if (lock_memory && !realtime_tools::lock_memory(message))
+  if (lock_memory)
   {
-    RCLCPP_WARN(cm->get_logger(), "Unable to lock the memory : '%s'", message.c_str());
+    const auto lock_result = realtime_tools::lock_memory();
+    if (!lock_result.first)
+    {
+      RCLCPP_WARN(cm->get_logger(), "Unable to lock the memory: '%s'", lock_result.second.c_str());
+    }
   }
 
   RCLCPP_INFO(cm->get_logger(), "update rate is %d Hz", cm->get_update_rate());