rtc: isl1208: 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/20210202112219.3610853-9-alexandre.belloni@bootlin.com

drivers/rtc/rtc-isl1208.c

@@ -99,7 +99,7 @@ static const struct i2c_device_id isl1208_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, isl1208_id);
 
-static const struct of_device_id isl1208_of_match[] = {
+static const __maybe_unused struct of_device_id isl1208_of_match[] = {
 	{ .compatible = "isil,isl1208", .data = &isl1208_configs[TYPE_ISL1208] },
 	{ .compatible = "isil,isl1209", .data = &isl1208_configs[TYPE_ISL1209] },
 	{ .compatible = "isil,isl1218", .data = &isl1208_configs[TYPE_ISL1218] },