atm: nicstar: Unmap DMA on send error

The `skb' is mapped for DMA in ns_send() but does not unmap DMA in case
push_scqe() fails to submit the `skb'. The memory of the `skb' is
released so only the DMA mapping is leaking.

Unmap the DMA mapping in case push_scqe() failed.

Fixes: 864a3ff ("atm: [nicstar] remove virt_to_bus() and support 64-bit platforms")
Cc: Chas Williams <3chas3@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/atm/nicstar.c

@@ -1706,6 +1706,8 @@ static int ns_send(struct atm_vcc *vcc, struct sk_buff *skb)
 
 	if (push_scqe(card, vc, scq, &scqe, skb) != 0) {
 		atomic_inc(&vcc->stats->tx_err);
+		dma_unmap_single(&card->pcidev->dev, NS_PRV_DMA(skb), skb->len,
+				 DMA_TO_DEVICE);
 		dev_kfree_skb_any(skb);
 		return -EIO;
 	}