drm: exynos: mark pm functions as __maybe_unused

The rework of the exynos DRM clock handling introduced
warnings for configurations that have CONFIG_PM disabled:

drivers/gpu/drm/exynos/exynos_hdmi.c:736:13: error: 'hdmi_clk_disable_gates' defined but not used [-Werror=unused-function]
 static void hdmi_clk_disable_gates(struct hdmi_context *hdata)
             ^~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/exynos/exynos_hdmi.c:717:12: error: 'hdmi_clk_enable_gates' defined but not used [-Werror=unused-function]
 static int hdmi_clk_enable_gates(struct hdmi_context *hdata)

The problem is that the PM functions themselves are inside of
an #ifdef, but some functions they call are not.

This patch removes the #ifdef and instead marks the PM functions
as __maybe_unused, which is a more reliable way to get it right.

Link: https://patchwork.kernel.org/patch/8436281/
Fixes: 9be7e9898444 ("drm/exynos/hdmi: clock code re-factoring")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_hdmi.c

@@ -1932,8 +1932,7 @@ static int hdmi_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM
-static int exynos_hdmi_suspend(struct device *dev)
+static int __maybe_unused exynos_hdmi_suspend(struct device *dev)
 {
 	struct hdmi_context *hdata = dev_get_drvdata(dev);
 
@@ -1942,7 +1941,7 @@ static int exynos_hdmi_suspend(struct device *dev)
 	return 0;
 }
 
-static int exynos_hdmi_resume(struct device *dev)
+static int __maybe_unused exynos_hdmi_resume(struct device *dev)
 {
 	struct hdmi_context *hdata = dev_get_drvdata(dev);
 	int ret;
@@ -1953,7 +1952,6 @@ static int exynos_hdmi_resume(struct device *dev)
 
 	return 0;
 }
-#endif
 
 static const struct dev_pm_ops exynos_hdmi_pm_ops = {
 	SET_RUNTIME_PM_OPS(exynos_hdmi_suspend, exynos_hdmi_resume, NULL)