Input: mpr121 - 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.
Suggested-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/mpr121_touchkey.c

@@ -266,8 +266,7 @@ static int mpr_touchkey_probe(struct i2c_client *client,
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
-static int mpr_suspend(struct device *dev)
+static int __maybe_unused mpr_suspend(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 
@@ -279,7 +278,7 @@ static int mpr_suspend(struct device *dev)
 	return 0;
 }
 
-static int mpr_resume(struct device *dev)
+static int __maybe_unused mpr_resume(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct mpr121_touchkey *mpr121 = i2c_get_clientdata(client);
@@ -292,7 +291,6 @@ static int mpr_resume(struct device *dev)
 
 	return 0;
 }
-#endif
 
 static SIMPLE_DEV_PM_OPS(mpr121_touchkey_pm_ops, mpr_suspend, mpr_resume);