Input: ektf2127 - mark PM functions as __maybe_unused

The newly added ektf2127 driver uses the SIMPLE_DEV_PM_OPS macro
to conditionally refer to the resume/suspend functions, which
causes a warning when CONFIG_PM_SLEEP is disabled:

drivers/input/touchscreen/ektf2127.c:168:12: error: 'ektf2127_resume' defined but not used [-Werror=unused-function]
drivers/input/touchscreen/ektf2127.c:156:12: error: 'ektf2127_suspend' defined but not used [-Werror=unused-function]

We could either put these functions inside of an #ifdef or
add __maybe_unused annotations. This uses the second approach,
which is generally more foolproof.

Fixes: 9ca5bf5029b6 ("Input: add support for Elan eKTF2127 touchscreen controller")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/ektf2127.c

@@ -153,7 +153,7 @@ static void ektf2127_stop(struct input_dev *dev)
 	gpiod_set_value_cansleep(ts->power_gpios, 0);
 }
 
-static int ektf2127_suspend(struct device *dev)
+static int __maybe_unused ektf2127_suspend(struct device *dev)
 {
 	struct ektf2127_ts *ts = i2c_get_clientdata(to_i2c_client(dev));
 
@@ -165,7 +165,7 @@ static int ektf2127_suspend(struct device *dev)
 	return 0;
 }
 
-static int ektf2127_resume(struct device *dev)
+static int __maybe_unused ektf2127_resume(struct device *dev)
 {
 	struct ektf2127_ts *ts = i2c_get_clientdata(to_i2c_client(dev));