sh-sci: extend PM methods

In order to make it possible to restore from hibernation not only in Linux but
also in e.g. U-Boot, we have to use sci_{suspend|remove}() for the PM {freeze|
thaw|restore}() methods.  It's handy to achieve this by using SIMPLE_DEV_PM_OPS()
macro, however we have to annotate sci_{suspend|remove}() with '__maybe_unused'
in order to avoid compilation warnings when CONFIG_PM_SLEEP is undefined.

Based on orignal patch by Mikhail Ulyanov <mikhail.ulyanov@cogentembedded.com>.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sh-sci.c

@@ -2605,7 +2605,7 @@ static int sci_probe(struct platform_device *dev)
 	return 0;
 }
 
-static int sci_suspend(struct device *dev)
+static __maybe_unused int sci_suspend(struct device *dev)
 {
 	struct sci_port *sport = dev_get_drvdata(dev);
 
@@ -2615,7 +2615,7 @@ static int sci_suspend(struct device *dev)
 	return 0;
 }
 
-static int sci_resume(struct device *dev)
+static __maybe_unused int sci_resume(struct device *dev)
 {
 	struct sci_port *sport = dev_get_drvdata(dev);
 
@@ -2625,10 +2625,7 @@ static int sci_resume(struct device *dev)
 	return 0;
 }
 
-static const struct dev_pm_ops sci_dev_pm_ops = {
-	.suspend	= sci_suspend,
-	.resume		= sci_resume,
-};
+static SIMPLE_DEV_PM_OPS(sci_dev_pm_ops, sci_suspend, sci_resume);
 
 static struct platform_driver sci_driver = {
 	.probe		= sci_probe,