iio: imu: adis16480: Deal with filter freq in a generic way

When setting the filter frequency, the driver looks into the
adis16480_def_filter_freqs table for the best match. Pass this table to
the chip_info struct since future devices will need to use a different
table.

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