spi: dt-bindings: Convert Freescale SPI bindings to YAML

fsl-spi.txt contains the bindings for the fsl,spi and fsl,espi
contollers. Convert them to YAML.

Reviewed-by: "Rob Herring (Arm)" <robh@kernel.org>
Signed-off-by: J. Neuschäfer <j.ne@posteo.net>
Link: https://patch.msgid.link/20250220-ppcyaml-spi-v3-1-e340613c7875@posteo.net


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