iio: adc: mt6360: Drop an incorrect __maybe_unused marking.

Given the struct platform_driver has one of it's elements assigned to
point to the of_device_id table, it is never going to be unused.

Drop the marking.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Gene Chen <gene_chen@richtek.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220807162121.862894-1-jic23@kernel.org

drivers/iio/adc/mt6360-adc.c

@@ -353,7 +353,7 @@ static int mt6360_adc_probe(struct platform_device *pdev)
 	return devm_iio_device_register(&pdev->dev, indio_dev);
 }
 
-static const struct of_device_id __maybe_unused mt6360_adc_of_id[] = {
+static const struct of_device_id mt6360_adc_of_id[] = {
 	{ .compatible = "mediatek,mt6360-adc", },
 	{}
 };