[tlgen] Fix US node lookup for socket M1

Use first list element of host DS as index to lookup US node index

Signed-off-by: Jan Van Winkel <jan.van_winkel@dxplore.eu>
diff --git a/util/tlgen/elaborate.py b/util/tlgen/elaborate.py
index 7a2f52a..e65b6b6 100644
--- a/util/tlgen/elaborate.py
+++ b/util/tlgen/elaborate.py
@@ -165,7 +165,7 @@
                      .format(dnode.name, dnode.hpass, dnode.hdepth))
 
         elif dnode.node_type == NodeType.SOCKET_M1:
-            idx = dnode.us.index(host.ds)
+            idx = dnode.us.index(host.ds[0])
             if full_fifo:
                 log.info("fifo present no bypass")
                 dnode.hpass = dnode.hpass & ~(1 << idx)