net: Remove __skb_insert() calls outside of skbuff internals.

This minor cleanup simplifies later changes which will convert
struct sk_buff and friends over to using struct list_head.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index ddccc07..98e0495 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -1864,7 +1864,7 @@
 	for (p = list->next; p != (struct sk_buff *)list; p = p->next)
 		if (seq_before(seq, p->sequence))
 			break;
-	__skb_insert(skb, p->prev, p, list);
+	__skb_queue_before(list, p, skb);
 }
 
 /*