Documentation: sdhci-msm: Add new compatible string for SDCC v5

For SDCC version 5.0.0 and higher, new compatible string
"qcom,sdhci-msm-v5" is added.

Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>
Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>