dt-bindings: fpga: Convert bridge binding to yaml

Convert the generic fpga bridge DT binding to json-schema.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Xu Yilun <yilun.xu@intel.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/14558a4dcfab5255c1683015287e9c7f48b1afc2.1704807147.git.michal.simek@amd.com


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