net: spider_net: Remove a useless memset

Avoid a memset after a call to 'dma_alloc_coherent()'.
This is useless since
commit 518a2f19 ("dma-mapping: zero memory returned from dma_alloc_*")
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

@@ -314,8 +314,6 @@ spider_net_init_chain(struct spider_net_card *card,
 	if (!chain->hwring)
 		return -ENOMEM;
 
-	memset(chain->ring, 0, chain->num_desc * sizeof(struct spider_net_descr));
-
 	/* Set up the hardware pointers in each descriptor */
 	descr = chain->ring;
 	hwdescr = chain->hwring;