Updating fixed size arrays to NdMatrix

Author: behzadmehmood

vpr/src/place/net_cost_handler.cpp

@@ -54,8 +54,8 @@ enum class NetUpdateState {
 
 const int MAX_FANOUT_CROSSING_COUNT = 50;
 
-double cong_matrix[400][400];
-double cong_matrix_new[400][400];
+vtr::NdMatrix<double, 2> cong_matrix;
+vtr::NdMatrix<double, 2> cong_matrix_new;
 
 /**
  * @brief Crossing counts for nets with different #'s of pins.  From