drm/stm: dsi: use new SYSTEM_SLEEP_PM_OPS() macro

Use RUNTIME_PM_OPS() instead of the old SET_SYSTEM_SLEEP_PM_OPS().
This means we don't need  __maybe_unused on the functions.
Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Acked-by: Yannick Fertre <yannick.fertre@foss.st.com>
Tested-by: Yannick Fertre <yannick.fertre@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240129104106.43141-2-raphael.gallais-pou@foss.st.com

drivers/gpu/drm/stm/dw_mipi_dsi-stm.c

@@ -544,7 +544,7 @@ static void dw_mipi_dsi_stm_remove(struct platform_device *pdev)
 	regulator_disable(dsi->vdd_supply);
 }
 
-static int __maybe_unused dw_mipi_dsi_stm_suspend(struct device *dev)
+static int dw_mipi_dsi_stm_suspend(struct device *dev)
 {
 	struct dw_mipi_dsi_stm *dsi = dw_mipi_dsi_stm_plat_data.priv_data;
 
@@ -556,7 +556,7 @@ static int __maybe_unused dw_mipi_dsi_stm_suspend(struct device *dev)
 	return 0;
 }
 
-static int __maybe_unused dw_mipi_dsi_stm_resume(struct device *dev)
+static int dw_mipi_dsi_stm_resume(struct device *dev)
 {
 	struct dw_mipi_dsi_stm *dsi = dw_mipi_dsi_stm_plat_data.priv_data;
 	int ret;
@@ -580,7 +580,7 @@ static int __maybe_unused dw_mipi_dsi_stm_resume(struct device *dev)
 }
 
 static const struct dev_pm_ops dw_mipi_dsi_stm_pm_ops = {
-	SET_SYSTEM_SLEEP_PM_OPS(dw_mipi_dsi_stm_suspend,
+	SYSTEM_SLEEP_PM_OPS(dw_mipi_dsi_stm_suspend,
 			    dw_mipi_dsi_stm_resume)
 };