drm: rcar-du: Remove #ifdef guards for PM related functions

Use the DEFINE_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr() macros to handle
the .suspend/.resume callbacks.

These macros allow the suspend and resume functions to be automatically
dropped by the compiler when CONFIG_SUSPEND is disabled, without having
to use #ifdef guards.

This has the advantage of always compiling these functions in,
independently of any Kconfig option. Thanks to that, bugs and other
regressions are subsequently easier to catch.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221129191942.138244-4-paul@crapouillou.net

drivers/gpu/drm/rcar-du/rcar_du_drv.c

@@ -599,7 +599,6 @@ static const struct drm_driver rcar_du_driver = {
  * Power management
  */
 
-#ifdef CONFIG_PM_SLEEP
 static int rcar_du_pm_suspend(struct device *dev)
 {
 	struct rcar_du_device *rcdu = dev_get_drvdata(dev);
@@ -613,11 +612,9 @@ static int rcar_du_pm_resume(struct device *dev)
 
 	return drm_mode_config_helper_resume(&rcdu->ddev);
 }
-#endif
 
-static const struct dev_pm_ops rcar_du_pm_ops = {
-	SET_SYSTEM_SLEEP_PM_OPS(rcar_du_pm_suspend, rcar_du_pm_resume)
-};
+static DEFINE_SIMPLE_DEV_PM_OPS(rcar_du_pm_ops,
+				rcar_du_pm_suspend, rcar_du_pm_resume);
 
 /* -----------------------------------------------------------------------------
  * Platform driver
@@ -712,7 +709,7 @@ static struct platform_driver rcar_du_platform_driver = {
 	.shutdown	= rcar_du_shutdown,
 	.driver		= {
 		.name	= "rcar-du",
-		.pm	= &rcar_du_pm_ops,
+		.pm	= pm_sleep_ptr(&rcar_du_pm_ops),
 		.of_match_table = rcar_du_of_table,
 	},
 };