[vpr][route][crr] don't add crr connections for switch blocks on the perimeter

Author: amin1377

vpr/src/route/rr_graph_generation/tileable_rr_graph/tileable_rr_graph_edge_builder.cpp

@@ -364,7 +364,9 @@ void build_rr_graph_regular_edges(const RRGraphView& rr_graph,
             /* adapt the switch_block_conn for the GSB nodes */
             t_track2track_map sb_conn; /* [0..from_gsb_side][0..chan_width-1][track_indices] */
             if (build_crr_edges) {
-                build_crr_gsb_track_to_track_edges(rr_graph_builder, rr_gsb, *crr_connection_builder);
+                if (ix != gsb_range.x() && iy != gsb_range.y()) {
+                    build_crr_gsb_track_to_track_edges(rr_graph_builder, rr_gsb, *crr_connection_builder);
+                }
             } else {
                 sb_conn = build_gsb_track_to_track_map(rr_graph,
                                                        rr_gsb,