Convert spi for Xilinx Zynq UltraScale+ MPSoC GQSPI bindings
documentation to YAML.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210613214317.296667-1-iwamatsu@nigauri.org


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