drm/tidss: Fix warning: unused variable 'tidss_pm_ops'

Mark 'tidss_pm_ops' as __maybe_unused to avoid
the warning: unused variable 'tidss_pm_ops'

Fixes: 6e120594 ("drm/tidss: Make use of the helper macro SET_RUNTIME_PM_OPS()")
Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211129063347.404-1-caihuoqing@baidu.com

drivers/gpu/drm/tidss/tidss_drv.c

@@ -88,7 +88,7 @@ static int __maybe_unused tidss_resume(struct device *dev)
 	return drm_mode_config_helper_resume(&tidss->ddev);
 }
 
-static const struct dev_pm_ops tidss_pm_ops = {
+static __maybe_unused const struct dev_pm_ops tidss_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(tidss_suspend, tidss_resume)
 	SET_RUNTIME_PM_OPS(tidss_pm_runtime_suspend, tidss_pm_runtime_resume, NULL)
 };