mmc: sdhci-msm: Support for getting DLL HSR values from dt file

Add support for getting dll hsr setting from device tree file and
to update the dll registers with these HSR settings.

HSR(Hardware Settings Reference) values of DLL specific registers in
SDHC controller would vary based on the process node. Getting these
values through device tree ensure the driver is agnostic of process
node changes.

Use actual clock instead of standard clock rate while configuring DLL
frequency. Otherwise, DLL frequency doesn't match with recommended
HSR value.

With this changes DDR config dt property redundant. So deleting it.

Change-Id: Id5da6189074ed365bef820262563dcb411bf22eb
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>