[IPV6]: Do not purge default routes by RA.

Signed-off-by: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ndisc.c

@@ -1078,13 +1078,6 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 			return;
 		}
 		neigh->flags |= NTF_ROUTER;
-
-		/*
-		 *	If we where using an "all destinations on link" route
-		 *	delete it
-		 */
-
-		rt6_purge_dflt_routers();
 	}
 
 	if (rt)