net: spider_net: Fix the size used in a 'dma_free_coherent()' call

Update the size used in 'dma_free_coherent()' in order to match the one
used in the corresponding 'dma_alloc_coherent()', in
'spider_net_init_chain()'.

Fixes: d4ed8f8d ("Spidernet DMA coalescing")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/toshiba/spider_net.c

@@ -283,8 +283,8 @@ spider_net_free_chain(struct spider_net_card *card,
 		descr = descr->next;
 	} while (descr != chain->ring);
 
-	dma_free_coherent(&card->pdev->dev, chain->num_desc,
-	    chain->hwring, chain->dma_addr);
+	dma_free_coherent(&card->pdev->dev, chain->num_desc * sizeof(struct spider_net_hw_descr),
+			  chain->hwring, chain->dma_addr);
 }
 
 /**