dt-bindings: mmc: samsung,exynos-dw-mshc: convert to dtschema

Convert the Samsung Exynos SoC specific extensions to the Synopsys
Designware Mobile Storage Host Controller to DT schema.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220605163710.144210-4-krzysztof.kozlowski@linaro.org


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>