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 <[e-mail]>
Cc: Gene Chen <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/iio/adc/mt6360-adc.c

···
 	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", },
 	{}
 };