iio: chemical: Add OF match table for CCS811 VOC sensor

Add devicetree OF match table support for CCS811 VOC sensor.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>