ARM: dts: msm: Add ddr config settings as a dt property for sdm670

sdm670 require a particular settings for SDCC_HC_REG_DDR_CONFIG
register so that HS400 mode in eMMC will work without crc errors.
Add this setting as a dt property so that the driver can read it
and set the register accordingly.

This particular setting (DLL bypass debug mode) was decided after
VI testing and calibrations on the msm.

Change-Id: I666a6aed4905ce23488930044b76af06801c4872
Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org>