Fix CONTROLLER_FAN options compile

Marlin/src/feature/controllerfan.h

@@ -58,7 +58,7 @@ class ControllerFan {
     #if ENABLED(CONTROLLER_FAN_EDITABLE)
       static controllerFan_settings_t settings;
     #else
-      static const controllerFan_settings_t &settings = controllerFan_defaults;
+      static const controllerFan_settings_t constexpr &settings = controllerFan_defaults;
     #endif
     static inline bool state() { return speed > 0; }
     static inline void init() { reset(); }