power: supply: lp8727_charger: mark OF related data as maybe unused

The driver can be compile tested with !CONFIG_OF making certain data
unused:

  drivers/power/supply/lp8727_charger.c:601:34: error: ‘lp8727_dt_ids’ defined but not used [-Werror=unused-const-variable=]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/lp8727_charger.c

@@ -598,7 +598,7 @@ static void lp8727_remove(struct i2c_client *cl)
 	lp8727_unregister_psy(pchg);
 }
 
-static const struct of_device_id lp8727_dt_ids[] = {
+static const struct of_device_id lp8727_dt_ids[] __maybe_unused = {
 	{ .compatible = "ti,lp8727", },
 	{ }
 };