mac80211_hwsim: fix-up build damage from removal of skb->dst

Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 1b59edc..93c1c4a 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -413,8 +413,7 @@
 
 	/* release the skb's source info */
 	skb_orphan(skb);
-	dst_release(skb->dst);
-	skb->dst = NULL;
+	skb_dst_drop(skb);
 	skb->mark = 0;
 	secpath_reset(skb);
 	nf_reset(skb);