net: moxa: Use devm_platform_get_and_ioremap_resource()

Use devm_platform_get_and_ioremap_resource() to simplify
code and avoid a null-ptr-deref by checking 'res' in it.

Signed-off-by: Yang Yingliang <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/moxa/moxart_ether.c

···
 	priv->ndev = ndev;
 	priv->pdev = pdev;
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	ndev->base_addr = res->start;
-	priv->base = devm_ioremap_resource(p_dev, res);
+	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
 	if (IS_ERR(priv->base)) {
 		ret = PTR_ERR(priv->base);
 		goto init_fail;
 	}
+	ndev->base_addr = res->start;
 
 	spin_lock_init(&priv->txlock);