[vpr][router] fix fuction signiture

Author: amin1377

vpr/src/route/route_utils.cpp

@@ -507,7 +507,11 @@ void try_graph(int width_fac,
                     is_flat);
 }
 
+#ifndef NO_GRAPHICS
 void update_draw_pres_fac(const float new_pres_fac) {
+#else
+void update_draw_pres_fac(const float /*new_pres_fac*/)
+#endif
 #ifndef NO_GRAPHICS
 
     // Only updates the drawing pres_fac if graphics is enabled