spi: spi-fsl-lpspi: Switch to SYSTEM_SLEEP_PM_OPS()

Replace SET_SYSTEM_SLEEP_PM_OPS with its modern SYSTEM_SLEEP_PM_OPS()
alternative.

The combined usage of pm_ptr() and SYSTEM_SLEEP_PM_OPS()
allows the compiler to evaluate if the runtime suspend/resume() functions
are used at build time or are simply dead code.

This allows removing the __maybe_unused notation from the runtime
suspend/resume() functions.
Signed-off-by: Fabio Estevam <festevam@denx.de>
Link: https://patch.msgid.link/20240625002023.228235-2-festevam@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-lpspi.c

@@ -960,13 +960,13 @@ static void fsl_lpspi_remove(struct platform_device *pdev)
 	pm_runtime_disable(fsl_lpspi->dev);
 }
 
-static int __maybe_unused fsl_lpspi_suspend(struct device *dev)
+static int fsl_lpspi_suspend(struct device *dev)
 {
 	pinctrl_pm_select_sleep_state(dev);
 	return pm_runtime_force_suspend(dev);
 }
 
-static int __maybe_unused fsl_lpspi_resume(struct device *dev)
+static int fsl_lpspi_resume(struct device *dev)
 {
 	int ret;
 
@@ -984,7 +984,7 @@ static int __maybe_unused fsl_lpspi_resume(struct device *dev)
 static const struct dev_pm_ops fsl_lpspi_pm_ops = {
 	SET_RUNTIME_PM_OPS(fsl_lpspi_runtime_suspend,
 				fsl_lpspi_runtime_resume, NULL)
-	SET_SYSTEM_SLEEP_PM_OPS(fsl_lpspi_suspend, fsl_lpspi_resume)
+	SYSTEM_SLEEP_PM_OPS(fsl_lpspi_suspend, fsl_lpspi_resume)
 };
 
 static struct platform_driver fsl_lpspi_driver = {