backlight: convert from legacy pm ops to dev_pm_ops

Convert drivers/video/backlight/class to use dev_pm_ops for power
management and remove Legacy PM ops hooks.

With this change, backlight class registers suspend/resume callbacks via
class->pm (dev_pm_ops) instead of Legacy class->suspend/resume.  When
__device_suspend() runs call-backs, it will find class->pm ops for the
backlight class.

[jg1.han@samsung.com: add CONFIG_PM_SLEEP to suspend/resume functions]
Signed-off-by: Shuah Khan <shuah.kh@samsung.com>
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Shuah Khan <shuahkhan@gmail.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Cc: Shuah Khan <shuahkhan@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/backlight/backlight.c

@@ -208,7 +208,8 @@ static ssize_t backlight_show_actual_brightness(struct device *dev,
 
 static struct class *backlight_class;
 
-static int backlight_suspend(struct device *dev, pm_message_t state)
+#ifdef CONFIG_PM_SLEEP
+static int backlight_suspend(struct device *dev)
 {
 	struct backlight_device *bd = to_backlight_device(dev);
 
@@ -235,6 +236,10 @@ static int backlight_resume(struct device *dev)
 
 	return 0;
 }
+#endif
+
+static SIMPLE_DEV_PM_OPS(backlight_class_dev_pm_ops, backlight_suspend,
+			 backlight_resume);
 
 static void bl_device_release(struct device *dev)
 {
@@ -489,8 +494,7 @@ static int __init backlight_class_init(void)
 	}
 
 	backlight_class->dev_attrs = bl_device_attributes;
-	backlight_class->suspend = backlight_suspend;
-	backlight_class->resume = backlight_resume;
+	backlight_class->pm = &backlight_class_dev_pm_ops;
 	return 0;
 }