mac802154: llsec: fix incorrect lock pairing

In encrypt, sec->lock is taken with read_lock_bh, so in the error path,
we must read_unlock_bh.

Signed-off-by: Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mac802154/llsec.c

@@ -776,7 +776,7 @@ int mac802154_llsec_encrypt(struct mac802154_llsec *sec, struct sk_buff *skb)
 	return rc < 0 ? rc : 0;
 
 fail_read:
-	read_unlock(&sec->lock);
+	read_unlock_bh(&sec->lock);
 fail:
 	rcu_read_unlock();
 	return rc;