Fix plan_arc clockwise (G2)

Fix #9482

Marlin/Marlin_main.cpp

@@ -12952,7 +12952,7 @@ void prepare_move_to_destination() {
       angular_travel = RADIANS(360);
 
     const float flat_mm = radius * angular_travel,
-                mm_of_travel = linear_travel ? HYPOT(flat_mm, linear_travel) : flat_mm;
+                mm_of_travel = linear_travel ? HYPOT(flat_mm, linear_travel) : FABS(flat_mm);
     if (mm_of_travel < 0.001) return;
 
     uint16_t segments = FLOOR(mm_of_travel / (MM_PER_ARC_SEGMENT));