Input: gpio_keys - annotate PM methods as __maybe_unused

Instead of using #ifdef, let's mark suspend and resume methods as
__maybe_unused to provide better compile coverage.
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/gpio_keys.c

@@ -814,8 +814,7 @@ static int gpio_keys_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
-static int gpio_keys_suspend(struct device *dev)
+static int __maybe_unused gpio_keys_suspend(struct device *dev)
 {
 	struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
 	struct input_dev *input = ddata->input;
@@ -837,7 +836,7 @@ static int gpio_keys_suspend(struct device *dev)
 	return 0;
 }
 
-static int gpio_keys_resume(struct device *dev)
+static int __maybe_unused gpio_keys_resume(struct device *dev)
 {
 	struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
 	struct input_dev *input = ddata->input;
@@ -863,7 +862,6 @@ static int gpio_keys_resume(struct device *dev)
 	gpio_keys_report_state(ddata);
 	return 0;
 }
-#endif
 
 static SIMPLE_DEV_PM_OPS(gpio_keys_pm_ops, gpio_keys_suspend, gpio_keys_resume);