thermal: imx_thermal: Use __maybe_unused instead of CONFIG_PM_SLEEP

Use __maybe_unused for power management related functions instead
of #if CONFIG_PM_SLEEP to simplify the code.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1583139266-23615-1-git-send-email-Anson.Huang@nxp.com

drivers/thermal/imx_thermal.c

@@ -878,8 +878,7 @@ static int imx_thermal_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
-static int imx_thermal_suspend(struct device *dev)
+static int __maybe_unused imx_thermal_suspend(struct device *dev)
 {
 	struct imx_thermal_data *data = dev_get_drvdata(dev);
 	struct regmap *map = data->tempmon;
@@ -900,7 +899,7 @@ static int imx_thermal_suspend(struct device *dev)
 	return 0;
 }
 
-static int imx_thermal_resume(struct device *dev)
+static int __maybe_unused imx_thermal_resume(struct device *dev)
 {
 	struct imx_thermal_data *data = dev_get_drvdata(dev);
 	struct regmap *map = data->tempmon;
@@ -918,7 +917,6 @@ static int imx_thermal_resume(struct device *dev)
 
 	return 0;
 }
-#endif
 
 static SIMPLE_DEV_PM_OPS(imx_thermal_pm_ops,
 			 imx_thermal_suspend, imx_thermal_resume);