dt-bindings: mmc: sdhci-msm: Document the SM8450 compatible

Document the compatible for SDHCI on SM8450.

Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220714123406.1919836-2-konrad.dybcio@somainline.org


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