iwlagn: downgrade BUG_ON in interrupt

This BUG_ON really shouldn't trigger, but if it does, as on my machine,
it leaves you wondering what happened because you won't see it. Let's
instead leak a bit of state and memory and at least make it possible to
report it to the kerneloops project to track it.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-tx.c

@@ -1200,10 +1200,9 @@ void iwl_tx_cmd_complete(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb)
 	/* If a Tx command is being handled and it isn't in the actual
 	 * command queue then there a command routing bug has been introduced
 	 * in the queue management code. */
-	if (txq_id != IWL_CMD_QUEUE_NUM)
-		IWL_ERROR("Error wrong command queue %d command id 0x%X\n",
-			  txq_id, pkt->hdr.cmd);
-	BUG_ON(txq_id != IWL_CMD_QUEUE_NUM);
+	if (WARN(txq_id != IWL_CMD_QUEUE_NUM,
+		 "wrong command queue %d, command id 0x%X\n", txq_id, pkt->hdr.cmd))
+		return;
 
 	cmd_index = get_cmd_index(&priv->txq[IWL_CMD_QUEUE_NUM].q, index, huge);
 	cmd = priv->txq[IWL_CMD_QUEUE_NUM].cmd[cmd_index];