iio: adc: ad9467: add support for ad9211

iio: adc: ad9467: add support for ad9211

The AD9211 is a 10-bit monolithic sampling analog-to-digital converter
optimized for high performance, low power, and ease of use. The product
operates at up to a 300 MSPS conversion rate and is optimized for
outstanding dynamic performance in wideband carrier and broadband systems.

The scale table implemented here is not an exact match with the
datasheet as the table presented there is missing some information.
The reference presents these values as being linear,
but that does not add up. There is information missing in the table.
Implemented scale table matches values at the middle and at the ends,
smoothing the curve towards middle and end.
Impact on end result from deviation in scale factor affects only software
using it for scaling. All the possible hw-settings are also available with
this implementation.

Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD9211.pdf
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>