ravb: stop reading ECMR in ravb_emac_init()

The code in ravb_emac_init() twiddling the ECMR bits always looked a bit
strange to me: if one intends to respect 'priv->duplex', why save old value
of the ECMR.DM bit?   As all the other bits are zeroed anyway, we don't
really need to read ECMR before writing to it.
Signed-off-by: NSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/ravb_main.c

@@ -338,16 +338,13 @@ static int ravb_ring_init(struct net_device *ndev, int q)
 static void ravb_emac_init(struct net_device *ndev)
 {
 	struct ravb_private *priv = netdev_priv(ndev);
-	u32 ecmr;
 
 	/* Receive frame limit set register */
 	ravb_write(ndev, ndev->mtu + ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN, RFLR);
 
 	/* PAUSE prohibition */
-	ecmr =  ravb_read(ndev, ECMR);
-	ecmr &= ECMR_DM;
-	ecmr |= ECMR_ZPF | (priv->duplex ? ECMR_DM : 0) | ECMR_TE | ECMR_RE;
-	ravb_write(ndev, ecmr, ECMR);
+	ravb_write(ndev, ECMR_ZPF | (priv->duplex ? ECMR_DM : 0) |
+		   ECMR_TE | ECMR_RE, ECMR);
 
 	ravb_set_rate(ndev);