Patch stepper.h for SCARA

Marlin/stepper.h

       static bool performing_homing;
     #endif
 
+    //
+    // Positions of stepper motors, in step units
+    //
+    static volatile long count_position[NUM_AXIS];
+
   private:
 
     static unsigned char last_direction_bits;        // The next stepping-bits to be output
     #endif
 
     //
-    // Positions of stepper motors, in step units
-    //
-    static volatile long count_position[NUM_AXIS];
-
-    //
     // Current direction of stepper motors (+1 or -1)
     //
     static volatile signed char count_direction[NUM_AXIS];
     static float get_axis_position_mm(AxisEnum axis);
 
     //
+    // SCARA AB axes are in degrees, not mm
+    //
+    #if IS_SCARA
+      static FORCE_INLINE float get_axis_position_degrees(AxisEnum axis) { return get_axis_position_mm(axis); }
+    #endif
+
+    //
     // The stepper subsystem goes to sleep when it runs out of things to execute. Call this
     // to notify the subsystem that it is time to go to work.
     //