Remove caching area for boxes upon batch_box run

Remove's caching from this and may lead to errors down the road

src/include/migraphx/op/nonmaxsuppression.hpp

@@ -141,7 +141,6 @@ struct nonmaxsuppression
     {
         std::array<double, 2> x;
         std::array<double, 2> y;
-        double stored_area;
 
         void sort()
         {
@@ -186,15 +185,14 @@ struct nonmaxsuppression
         }
 
         result.sort();
-        result.stored_area = result.area();
 
         return result;
     }
 
     inline bool suppress_by_iou(box b1, box b2, double iou_threshold) const
     {
-        const double area1 = b1.stored_area;
-        const double area2 = b2.stored_area;
+        const double area1 = b1.area();
+        const double area2 = b2.area();
 
         if(area1 <= .0f or area2 <= .0f)
         {