wan/fsl_ucc_hdlc: use dma_zalloc_coherent instead of allocator/memset

Use dma_zalloc_coherent instead of dma_alloc_coherent
followed by memset 0.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wan/fsl_ucc_hdlc.c

@@ -270,7 +270,7 @@ static int uhdlc_init(struct ucc_hdlc_private *priv)
 	iowrite16be(DEFAULT_HDLC_ADDR, &priv->ucc_pram->haddr4);
 
 	/* Get BD buffer */
-	bd_buffer = dma_alloc_coherent(priv->dev,
+	bd_buffer = dma_zalloc_coherent(priv->dev,
 					(RX_BD_RING_LEN + TX_BD_RING_LEN) *
 					MAX_RX_BUF_LENGTH,
 					&bd_dma_addr, GFP_KERNEL);
@@ -281,9 +281,6 @@ static int uhdlc_init(struct ucc_hdlc_private *priv)
 		goto free_tiptr;
 	}
 
-	memset(bd_buffer, 0, (RX_BD_RING_LEN + TX_BD_RING_LEN)
-			* MAX_RX_BUF_LENGTH);
-
 	priv->rx_buffer = bd_buffer;
 	priv->tx_buffer = bd_buffer + RX_BD_RING_LEN * MAX_RX_BUF_LENGTH;