rtc: rs5c372: quiet maybe-unused variable warning

When CONFIG_OF is disabled then the matching table is not referenced.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210202112219.3610853-14-alexandre.belloni@bootlin.com

drivers/rtc/rtc-rs5c372.c

@@ -83,7 +83,7 @@ static const struct i2c_device_id rs5c372_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, rs5c372_id);
 
-static const struct of_device_id rs5c372_of_match[] = {
+static const __maybe_unused struct of_device_id rs5c372_of_match[] = {
 	{
 		.compatible = "ricoh,r2025sd",
 		.data = (void *)rtc_r2025sd