routing: fix crash caused by loopback

routing: fix crash caused by loopback

	The rtentry member in node struct was used either as a
	listhead for routing entry list or as a link entry for the
	list of default routed streams. However, looped back input nodes
	behave both as device and stream nodes. As a result the same
	rtentry was used improperly in two different linked list and
	eventually lead to mysterious crashes. This problem is fixed
	by adding a new list entry (rtprilist) to the node struct.
	rtprilist is used to chain the default routed streams.