sh_eth: enclose PM code into #ifdef CONFIG_PM

Put '#ifdef CONFIG_PM' around sh_eth_runtime_nop() and 'sh_eth_dev_pm_ops'.
Add '#define SH_ETH_PM_OPS' to facilitate initialization of driver's 'pm' field
depending on whether CONFIG_PM is enabled.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
[Sergei: added the changelog, reworded the subject, changing the prefix.]
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -2673,6 +2673,7 @@ static int sh_eth_drv_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM
 static int sh_eth_runtime_nop(struct device *dev)
 {
 	/*
@@ -2686,17 +2687,21 @@ static int sh_eth_runtime_nop(struct device *dev)
 	return 0;
 }
 
-static struct dev_pm_ops sh_eth_dev_pm_ops = {
+static const struct dev_pm_ops sh_eth_dev_pm_ops = {
 	.runtime_suspend = sh_eth_runtime_nop,
 	.runtime_resume = sh_eth_runtime_nop,
 };
+#define SH_ETH_PM_OPS (&sh_eth_dev_pm_ops)
+#else
+#define SH_ETH_PM_OPS NULL
+#endif
 
 static struct platform_driver sh_eth_driver = {
 	.probe = sh_eth_drv_probe,
 	.remove = sh_eth_drv_remove,
 	.driver = {
 		   .name = CARDNAME,
-		   .pm = &sh_eth_dev_pm_ops,
+		   .pm = SH_ETH_PM_OPS,
 	},
 };