More constraint on axis_unhomed_error

Marlin/Marlin.h

@@ -426,7 +426,7 @@ void do_blocking_move_to_z(const float &z, const float &fr_mm_s=0.0);
 void do_blocking_move_to_xy(const float &x, const float &y, const float &fr_mm_s=0.0);
 
 #if ENABLED(Z_PROBE_ALLEN_KEY) || ENABLED(Z_PROBE_SLED) || HAS_PROBING_PROCEDURE || HOTENDS > 1 || ENABLED(NOZZLE_CLEAN_FEATURE) || ENABLED(NOZZLE_PARK_FEATURE)
-  bool axis_unhomed_error(const bool x, const bool y, const bool z);
+  bool axis_unhomed_error(const bool x=true, const bool y=true, const bool z=true);
 #endif
 
 /**