Use the disable macros on initialization. Which fixes a bug when there is no pin defined for stepper enabled (motherboard 4)

Marlin/stepper.cpp

@@ -824,38 +824,36 @@ void st_init()
   #if (X_STEP_PIN > -1) 
     SET_OUTPUT(X_STEP_PIN);
     WRITE(X_STEP_PIN,INVERT_X_STEP_PIN);
-    if(!X_ENABLE_ON) WRITE(X_ENABLE_PIN,HIGH);
+    disable_x();
   #endif  
   #if (Y_STEP_PIN > -1) 
     SET_OUTPUT(Y_STEP_PIN);
     WRITE(Y_STEP_PIN,INVERT_Y_STEP_PIN);
-    if(!Y_ENABLE_ON) WRITE(Y_ENABLE_PIN,HIGH);
+    disable_y();
   #endif  
   #if (Z_STEP_PIN > -1) 
     SET_OUTPUT(Z_STEP_PIN);
     WRITE(Z_STEP_PIN,INVERT_Z_STEP_PIN);
-    if(!Z_ENABLE_ON) WRITE(Z_ENABLE_PIN,HIGH);
-    
     #if defined(Z_DUAL_STEPPER_DRIVERS) && (Z2_STEP_PIN > -1)
       SET_OUTPUT(Z2_STEP_PIN);
       WRITE(Z2_STEP_PIN,INVERT_Z_STEP_PIN);
-      if(!Z_ENABLE_ON) WRITE(Z2_ENABLE_PIN,HIGH);
     #endif
+    disable_z();
   #endif  
   #if (E0_STEP_PIN > -1) 
     SET_OUTPUT(E0_STEP_PIN);
     WRITE(E0_STEP_PIN,INVERT_E_STEP_PIN);
-    if(!E_ENABLE_ON) WRITE(E0_ENABLE_PIN,HIGH);
+    disable_e0();
   #endif  
   #if defined(E1_STEP_PIN) && (E1_STEP_PIN > -1) 
     SET_OUTPUT(E1_STEP_PIN);
     WRITE(E1_STEP_PIN,INVERT_E_STEP_PIN);
-    if(!E_ENABLE_ON) WRITE(E1_ENABLE_PIN,HIGH);
+    disable_e1();
   #endif  
   #if defined(E2_STEP_PIN) && (E2_STEP_PIN > -1) 
     SET_OUTPUT(E2_STEP_PIN);
     WRITE(E2_STEP_PIN,INVERT_E_STEP_PIN);
-    if(!E_ENABLE_ON) WRITE(E2_ENABLE_PIN,HIGH);
+    disable_e2();
   #endif  
 
   #ifdef CONTROLLERFAN_PIN