spi: dt-bindings: qcom,spi-qup: convert to dtschema

Convert the Qualcomm Universal Peripheral (QUP) Serial Peripheral
Interface (SPI) bindings to DT Schema.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Kuldeep Singh <singh.kuldeep87k@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220405063451.12011-7-krzysztof.kozlowski@linaro.org