mmc: sdhci-msm: Update DDR_CONFIG reg with HSR value if supplied

Update DDR_CONFIG register with HSR value if HSR value is supplied
in the device tree.

Change-Id: Iffabe98ae2fe2bcc74926a7527efa7fa38bedd11
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
Signed-off-by: Sarthak Garg <sartgarg@codeaurora.org>