mmc: sdhci-msm: Add HS400 platform support

The following msm platform specific changes are added to support HS400.
- Enable CDC calibration fixed feedback and sleep clock.
- Allow tuning for HS400 mode.
- Add capability to parse and configure pull settings for RCLK pin.
- Configure HS400 timing mode using the VENDOR_SPECIFIC_FUNC register.

Change-Id: I1304fe0f01df493ead48bf9ff3c7baee5ab040d4
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>