Rename netdev_*route to end in route4

Functions for IPv6 will be added soon afterwards. Also take the chance
to check for address length in sgsnemu and only apply the route if the
address matches.

Change-Id: Ic6c1b3c11c56f047e6e8c6f1040257fd62afea0f
diff --git a/lib/tun.c b/lib/tun.c
index 1aeed55..c771b92 100644
--- a/lib/tun.c
+++ b/lib/tun.c
@@ -276,7 +276,7 @@
 {
 
 	if (tun->routes) {
-		netdev_delroute(&tun->dstaddr.v4, &tun->addr.v4, &tun->netmask);
+		netdev_delroute4(&tun->dstaddr.v4, &tun->addr.v4, &tun->netmask);
 	}
 
 	if (tun->fd >= 0) {