Fix stepper use before init. Add Ultimaker2+ Extended clone config (#13284)

Marlin/src/module/configuration_store.cpp

   //
 
   #if HAS_MOTOR_CURRENT_PWM
-    uint32_t tmp_motor_current_setting[3] = PWM_MOTOR_CURRENT;
+    constexpr uint32_t tmp_motor_current_setting[3] = PWM_MOTOR_CURRENT;
     for (uint8_t q = 3; q--;)
       stepper.digipot_current(q, (stepper.motor_current_setting[q] = tmp_motor_current_setting[q]));
   #endif

Marlin/src/module/stepper.cpp

 
 Stepper stepper; // Singleton
 
+#if HAS_MOTOR_CURRENT_PWM
+  bool Stepper::initialized; // = false
+#endif
+
 #ifdef __AVR__
   #include "speed_lookuptable.h"
 #endif
     | (INVERT_Z_DIR ? _BV(Z_AXIS) : 0);
 
   set_directions();
+  #if HAS_MOTOR_CURRENT_PWM
+    initialized = true;
+  #endif
 }
 
 /**
 #if HAS_MOTOR_CURRENT_PWM
 
   void Stepper::refresh_motor_power() {
+    if (!initialized) return;
     LOOP_L_N(i, COUNT(motor_current_setting)) {
       switch (i) {
         #if PIN_EXISTS(MOTOR_CURRENT_PWM_XY) || PIN_EXISTS(MOTOR_CURRENT_PWM_X) || PIN_EXISTS(MOTOR_CURRENT_PWM_Y)
 
       #elif HAS_MOTOR_CURRENT_PWM
 
+        if (!initialized) return;
+
         if (WITHIN(driver, 0, COUNT(motor_current_setting) - 1))
           motor_current_setting[driver] = current; // update motor_current_setting
 

Marlin/src/module/stepper.h

         #define PWM_MOTOR_CURRENT DEFAULT_PWM_MOTOR_CURRENT
       #endif
       static uint32_t motor_current_setting[3];
+      static bool initialized;
     #endif
 
   private:

Marlin/src/pins/pins_ULTIMAIN_2.h

   #define FAN_PIN           7
 #endif
 
+#define ORIG_E0_AUTO_FAN_PIN 77
+
 //
 // Misc. Functions
 //