sh_eth: fix DMA channel misreporting

Currently 'ifconfig' for the Ethernet devices handled by this driver  shows
"DMA chan: ff" while the driver doesn't use any DMA channels. Not assigning
a value to 'net_device::dma' causes 'ifconfig'  to  correctly not report  a
DMA channel.
Signed-off-by: NSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -2996,7 +2996,6 @@ static int sh_eth_drv_probe(struct platform_device *pdev)
 	if (devno < 0)
 		devno = 0;
 
-	ndev->dma = -1;
 	ret = platform_get_irq(pdev, 0);
 	if (ret < 0)
 		goto out_release;