dt-bindings: iio: dac: use spi-peripheral-props.yaml

Instead of listing directly properties typical for SPI peripherals,
reference the spi-peripheral-props.yaml schema. This allows using all
properties typical for SPI-connected devices, even these which device
bindings author did not tried yet.

Remove the spi-* properties which now come via spi-peripheral-props.yaml
schema, except for the cases when device schema adds some constraints
like maximum frequency.

While changing additionalProperties->unevaluatedProperties, put it in
typical place, just before example DTS.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220816124321.67817-5-krzysztof.kozlowski@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

dt-bindings: iio: dac: adi,ad5755: drop unrelated included.

Probably a cut and paste error, but the binding header used in the
example is for the wrong device and nothing from it is used.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Sean Nyekjaer <sean.nyekjaer@prevas.dk>
Reviewed-by: Rob Herring <robh@kernel.org>

dt-bindings:iio:dac:ad5755: txt to yaml format conversion.

Straight forward conversion. Only fiddly bit is the XOR of
spi-cpol and spi-cpha.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Sean Nyekjaer <sean.nyekjaer@prevas.dk>
Link: https://lore.kernel.org/r/20201031184854.745828-40-jic23@kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210424173015.534941-1-jic23@kernel.org