ARM: dts: msm: Add SD card support for SDM670 QRD platform

SDM670 QRD platform device tree has no SD card
host controller sdhc_2 node. This change enables
SD card support by adding SD card host controller
node sdhc_2 into device tree.

Change-Id: Ia43a9a5ca644ae7be9d1537ceac1aca14cce3f6e
Signed-off-by: Can Guo <cang@codeaurora.org>