Simpler report_current_position for SCARA

Marlin/Marlin_main.cpp

   stepper.report_positions();
 
   #if IS_SCARA
-    SERIAL_PROTOCOLPGM("SCARA Theta:");
-    SERIAL_PROTOCOL(delta[A_AXIS]);
-    SERIAL_PROTOCOLPGM("   Psi+Theta:");
-    SERIAL_PROTOCOLLN(delta[B_AXIS]);
-
-    SERIAL_PROTOCOLPGM("SCARA Cal - Theta:");
-    SERIAL_PROTOCOL(delta[A_AXIS]);
-    SERIAL_PROTOCOLPGM("   Psi+Theta (90):");
-    SERIAL_PROTOCOLLN(delta[B_AXIS] - delta[A_AXIS] - 90);
-
-    SERIAL_PROTOCOLPGM("SCARA step Cal - Theta:");
-    SERIAL_PROTOCOL(delta[A_AXIS] / 90 * planner.axis_steps_per_mm[A_AXIS]);
-    SERIAL_PROTOCOLPGM("   Psi+Theta:");
-    SERIAL_PROTOCOLLN((delta[B_AXIS] - delta[A_AXIS]) / 90 * planner.axis_steps_per_mm[A_AXIS]);
+    SERIAL_PROTOCOLPAIR("SCARA Theta:", stepper.get_axis_position_mm(A_AXIS));
+    SERIAL_PROTOCOLLNPAIR("   Psi+Theta:", stepper.get_axis_position_mm(B_AXIS));
     SERIAL_EOL;
   #endif
 }

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];