dt-bindings: bus: convert qcom,ssbi schema to YAML format

Convert arm/msm/ssbi.txt yo YAML, moving it to the directory with bus
bindings.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230822001349.899298-4-dmitry.baryshkov@linaro.org


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