6lowpan: use rb_entry()

To make the code clearer, use rb_entry() instead of container_of() to
deal with rbtree.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/6lowpan/nhc.c

@@ -27,7 +27,7 @@ static int lowpan_nhc_insert(struct lowpan_nhc *nhc)
 
 	/* Figure out where to put new node */
 	while (*new) {
-		struct lowpan_nhc *this = container_of(*new, struct lowpan_nhc,
+		struct lowpan_nhc *this = rb_entry(*new, struct lowpan_nhc,
 						   node);
 		int result, len_dif, len;
 
@@ -69,7 +69,7 @@ static struct lowpan_nhc *lowpan_nhc_by_nhcid(const struct sk_buff *skb)
 	const u8 *nhcid_skb_ptr = skb->data;
 
 	while (node) {
-		struct lowpan_nhc *nhc = container_of(node, struct lowpan_nhc,
+		struct lowpan_nhc *nhc = rb_entry(node, struct lowpan_nhc,
 						  node);
 		u8 nhcid_skb_ptr_masked[LOWPAN_NHC_MAX_ID_LEN];
 		int result, i;