batman-adv: Count all non-success TX packets as dropped

A failure during the submission also causes dropped packets.
batadv_interface_tx should therefore also increase the DROPPED counter for
these returns.
Signed-off-by: NSven Eckelmann <sven@narfation.org>
Signed-off-by: NSimon Wunderlich <sw@simonwunderlich.de>

net/batman-adv/soft-interface.c

@@ -386,7 +386,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
 			ret = batadv_send_skb_via_tt(bat_priv, skb, dst_hint,
 						     vid);
 		}
-		if (ret == NET_XMIT_DROP)
+		if (ret != NET_XMIT_SUCCESS)
 			goto dropped_freed;
 	}