dt-bindings: spi: axi-spi-engine: convert to yaml

This converts the axi-spi-engine binding to yaml.

There are a few minor fixes in the conversion:
* Added maintainers.
* Added descriptions for the clocks.
* Fixed the double "@" in the example.
* Added a comma between the clocks in the example.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231117-axi-spi-engine-series-1-v1-1-cc59db999b87@baylibre.com


Signed-off-by: Mark Brown <broonie@kernel.org>