🐛 Fix M420 / M851 reports (#22829)

Followup to 79c72ed821

Marlin/src/gcode/bedlevel/M420.cpp

@@ -251,7 +251,7 @@ void GcodeSuite::M420_report(const bool forReplay/*=true*/) {
     #if ENABLED(ENABLE_LEVELING_FADE_HEIGHT)
       , SP_Z_STR, LINEAR_UNIT(planner.z_fade_height)
     #endif
-    , " ; Leveling "
+    , PSTR(" ; Leveling ")
   );
   serialprintln_onoff(planner.leveling_active);
 }