dt-bindings: iio: resolver: add devicetree bindings for ad2s1210

This adds new DeviceTree bindings for the Analog Devices, Inc. AD2S1210
resolver-to-digital converter.

Co-developed-by: Apelete Seketeli <aseketeli@baylibre.com>
Signed-off-by: Apelete Seketeli <aseketeli@baylibre.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230929-ad2s1210-mainline-v3-1-fa4364281745@baylibre.com


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