Cleanup to planner.cpp

Marlin/planner.cpp

    * Having the real displacement of the head, we can calculate the total movement length and apply the desired speed.
    */
   #if IS_CORE
-    float delta_mm[7];
+    float delta_mm[Z_HEAD + 1];
     #if CORE_IS_XY
       delta_mm[X_HEAD] = da * steps_to_mm[A_AXIS];
       delta_mm[Y_HEAD] = db * steps_to_mm[B_AXIS];
       delta_mm[C_AXIS] = CORESIGN(db - dc) * steps_to_mm[C_AXIS];
     #endif
   #else
-    float delta_mm[4];
+    float delta_mm[XYZE];
     delta_mm[X_AXIS] = da * steps_to_mm[X_AXIS];
     delta_mm[Y_AXIS] = db * steps_to_mm[Y_AXIS];
     delta_mm[Z_AXIS] = dc * steps_to_mm[Z_AXIS];
 
   // Slow down when the buffer starts to empty, rather than wait at the corner for a buffer refill
   #if ENABLED(SLOWDOWN) || ENABLED(ULTRA_LCD) || defined(XY_FREQUENCY_LIMIT)
+    // Segment time im micro seconds
     unsigned long segment_time = lround(1000000.0 / inverse_mm_s);
   #endif
   #if ENABLED(SLOWDOWN)
-    // Segment time im micro seconds
     if (moves_queued > 1 && moves_queued < (BLOCK_BUFFER_SIZE) / 2) {
       if (segment_time < min_segment_time) {
         // buffer is draining, add extra time.  The amount of time added increases if the buffer is still emptied more.

Marlin/planner.h

     #endif
 
     #if ENABLED(AUTOTEMP)
-      static float autotemp_max;
-      static float autotemp_min;
-      static float autotemp_factor;
+      static float autotemp_min, autotemp_max, autotemp_factor;
       static bool autotemp_enabled;
       static void getHighESpeed();
       static void autotemp_M104_M109();