🐛 Fix Chiron new TFT SD print after reset (#23855)

Marlin/src/gcode/bedlevel/mbl/G29.cpp

@@ -118,9 +118,11 @@ void GcodeSuite::G29() {
       // For each G29 S2...
       if (mbl_probe_index == 0) {
         // Move close to the bed before the first point
-        do_blocking_move_to_z(0.4f
+        do_blocking_move_to_z(
           #ifdef MANUAL_PROBE_START_Z
-            + (MANUAL_PROBE_START_Z) - 0.4f
+            MANUAL_PROBE_START_Z
+          #else
+            0.4f
           #endif
         );
       }