Add more leveling-debug output

Marlin/Marlin_main.cpp

 #endif
 
 static void set_axis_is_at_home(AxisEnum axis) {
+  #if ENABLED(DEBUG_LEVELING_FEATURE)
+    if (DEBUGGING(LEVELING)) {
+      SERIAL_ECHOPAIR("set_axis_is_at_home(", (unsigned long)axis);
+      SERIAL_ECHOLNPGM(") >>>");
+    }
+  #endif
 
   #if ENABLED(DUAL_X_CARRIAGE)
     if (axis == X_AXIS) {
     max_pos[axis] = base_max_pos(axis) + home_offset[axis];
 
     #if ENABLED(AUTO_BED_LEVELING_FEATURE) && Z_HOME_DIR < 0
-      if (axis == Z_AXIS) current_position[Z_AXIS] -= zprobe_zoffset;
+      if (axis == Z_AXIS) {
+        current_position[Z_AXIS] -= zprobe_zoffset;
+        #if ENABLED(DEBUG_LEVELING_FEATURE)
+          if (DEBUGGING(LEVELING)) SERIAL_ECHOPAIR("> zprobe_zoffset==", zprobe_zoffset);
+        #endif
+      }
     #endif
 
     #if ENABLED(DEBUG_LEVELING_FEATURE)
       if (DEBUGGING(LEVELING)) {
-        SERIAL_ECHOPAIR("set_axis_is_at_home ", (unsigned long)axis);
-        SERIAL_ECHOPAIR(" > (home_offset[axis]==", home_offset[axis]);
-        print_xyz(") > current_position", current_position);
+        SERIAL_ECHOPAIR("> home_offset[axis]==", home_offset[axis]);
+        print_xyz(" > current_position", current_position);
       }
     #endif
   }
+  #if ENABLED(DEBUG_LEVELING_FEATURE)
+    if (DEBUGGING(LEVELING)) {
+      SERIAL_ECHOPAIR("<<< set_axis_is_at_home(", (unsigned long)axis);
+      SERIAL_ECHOLNPGM(")");
+    }
+  #endif
 }
 
 /**
   #endif
 
   #if ENABLED(ENDSTOPS_ONLY_FOR_HOMING)
+    enable_endstops(false);
     #if ENABLED(DEBUG_LEVELING_FEATURE)
       if (DEBUGGING(LEVELING)) {
         SERIAL_ECHOLNPGM("ENDSTOPS_ONLY_FOR_HOMING enable_endstops(false)");
       }
     #endif
-    enable_endstops(false);
   #endif
 
   // For mesh leveling move back to Z=0
     #if ENABLED(DEBUG_LEVELING_FEATURE)
       if (DEBUGGING(LEVELING)) {
         SERIAL_ECHOLNPGM("gcode_G29 >>>");
+        print_xyz("> current_position", current_position);
       }
     #endif