staging: iio: adt7316: create of_device_id array

Create structure of type of_device_id in order to register all devices
the driver is able to manage.

Signed-off-by: Bárbara Fernandes <barbara.fernandes@usp.br>
Signed-off-by: Wilson Sales <spoonm@spoonm.org>
Co-developed-by: Wilson Sales <spoonm@spoonm.org>
Acked-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>