arm64: dts: qcom: sm6375: Add SDHCI2

Configure the second SDHCI bus controller, which usually the
interface used for SD cards.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221114105043.36698-3-konrad.dybcio@linaro.org