mmc: host: add SDHCI platform driver for msm chipsets

This platform driver adds the support of Secure Digital Host
Controller Interface compliant controller in MSM chipsets.

Change-Id: Ide3a658ad51a3c3d4a05c47c0e8f013f647c9516
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>