iio: adxl372_i2c: Add OF device ID table

The driver does not have a struct of_device_id table, but supported
devices are registered via Device Trees. This patch adds OF device ID
table.

Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>