staging: iio: resolver: ad2s1210: implement fault events

staging: iio: resolver: ad2s1210: implement fault events

When reading the position and velocity on the AD2S1210, there is also a
3rd byte following the two data bytes that contains the fault flag bits.
This patch adds support for reading this byte and generating events when
faults occur.

The faults are mapped to various channels and event type in order to
have a unique event for each fault.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231005-ad2s1210-mainline-v4-13-ec00746840fc@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>