Staging: iio: adt7316: Add of_device_id table

When the kernel starts up, it kicks off compiled-in drivers
that match “compatible” entries it finds in the device tree.
At a later stage (when /lib/modules is available), all kernel modules
that match “compatible” entries in the device tree are loaded.

But if there is no dt table then there should be a fall back path
with which desired kernel modules can be loaded. Hence, add
of_device_id table in the i2c driver to be able to use when there
is no dt table.

Signed-off-by: Shreeya Patel <shreeya.patel23498@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>