dt-bindings: rtc: zynqmp: convert bindings to YAML

Convert Real Time Clock for Xilinx Zynq MPSoC SoC bindings documentation
to YAML schemas.
And this renamed the file to compatible string of DT.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Link: https://lore.kernel.org/r/20210613205022.292575-1-iwamatsu@nigauri.org


Signed-off-by: Rob Herring <robh@kernel.org>