mac802154: properly free incoming skbs on decryption failure

mac802154 RX did not free skbs on decryption failure, assuming that the
caller would when the local rx handler returned _DROP. This was false.

Signed-off-by: Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mac802154/wpan.c b/net/mac802154/wpan.c
index 23bc91c..c8cfd54 100644
--- a/net/mac802154/wpan.c
+++ b/net/mac802154/wpan.c
@@ -472,6 +472,7 @@
 	rc = mac802154_llsec_decrypt(&sdata->sec, skb);
 	if (rc) {
 		pr_debug("decryption failed: %i\n", rc);
+		kfree_skb(skb);
 		return NET_RX_DROP;
 	}