dt-bindings: slimbus: qcom,slim-ngd: convert to DT schema

dt-bindings: slimbus: qcom,slim-ngd: convert to DT schema

Convert the Qualcomm SoC SLIMBus Non Generic Device (NGD) controller
bindings to DT Schema.

During conversion add iommus already present in DTS and extend the
example based on SDM845.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20221118065246.6835-13-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>