6lowpan: double unlock on an error path

We already unlocked a few lines earlier here, so we can go directly to
drop without passing through unlock.  This was introduced recently in
c5d3687 ('6lowpan: read data from skb safely').

Signed-off-by: Dan Carpenter <[email protected]>
Acked-by: Alexander Smirnov <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

net/ieee802154/6lowpan.c

@@ -771,7 +771,7 @@ lowpan_process_data(struct sk_buff *skb)
 			kfree(frame);
 
 			if (lowpan_fetch_skb_u8(skb, &iphc0))
-				goto unlock_and_drop;
+				goto drop;
 
 			break;
 		}