[IPV6]: Remove useless code from fib6_del_route().

There are useless codes in fib6_del_route(). The following patch has
been tested, every thing looks fine, as usual.

Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index df05c6f..7165a5e 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1126,9 +1126,6 @@
 
 	rt->u.dst.rt6_next = NULL;
 
-	if (fn->leaf == NULL && fn->fn_flags&RTN_TL_ROOT)
-		fn->leaf = &ip6_null_entry;
-
 	/* If it was last route, expunge its radix tree node */
 	if (fn->leaf == NULL) {
 		fn->fn_flags &= ~RTN_RTINFO;