staging: iio: resolver: ad2s1210: implement hysteresis as channel attr

The AD2S1210 resolver has a hysteresis feature that can be used to
prevent flicker in the LSB of the position register. This can be either
enabled or disabled. Disabling hysteresis is useful for increasing
precision by oversampling.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231005-ad2s1210-mainline-v4-2-ec00746840fc@baylibre.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>