mpl: increase number of perturbations for large arrays

     of interconnected macros due to the new connections

Signed-off-by: Arthur Koucher <arthurkoucher@precisioninno.com>

Author: AcKoucher

src/mpl/src/hier_rtlmp.cpp

@@ -2170,7 +2170,7 @@ void HierRTLMP::placeMacros(Cluster* cluster)
 
     // Large arrays need more steps to properly converge.
     if (large_macro_cluster) {
-      perturbations_per_step *= 2;
+      perturbations_per_step *= 4;
     }
   }