🐛 Fix BACKLASH_COMPENSATION compile (#24072)

Followup to #23826

Marlin/src/feature/backlash.cpp

@@ -162,8 +162,9 @@ int32_t Backlash::get_applied_steps(const AxisEnum axis) {
 }
 
 class Backlash::StepAdjuster {
+  private:
     xyz_long_t applied_steps;
-public:
+  public:
     StepAdjuster() {
       LOOP_NUM_AXES(axis) applied_steps[axis] = backlash.get_applied_steps((AxisEnum)axis);
     }
@@ -173,21 +174,25 @@ public:
     }
 };
 
-void Backlash::set_correction_uint8(const uint8_t v) {
+#if ENABLED(BACKLASH_GCODE)
+
+  void Backlash::set_correction_uint8(const uint8_t v) {
     StepAdjuster adjuster;
     correction = v;
-}
+  }
 
-void Backlash::set_distance_mm(const AxisEnum axis, const float v) {
+  void Backlash::set_distance_mm(const AxisEnum axis, const float v) {
     StepAdjuster adjuster;
     distance_mm[axis] = v;
-}
+  }
 
-#ifdef BACKLASH_SMOOTHING_MM
+  #ifdef BACKLASH_SMOOTHING_MM
     void Backlash::set_smoothing_mm(const float v) {
       StepAdjuster adjuster;
       smoothing_mm = v;
     }
+  #endif
+
 #endif
 
 #if ENABLED(MEASURE_BACKLASH_WHEN_PROBING)