ARM: dts: msm: add SD card detect pinctrl for SDM670 QRD platform

Add SD card detect pinctrl settings sdc2_cd_on and sdc2_cd_off to
SDM670 QRD platform. Without this change, the SD card could not
be detected during boot-up or hot-plug

Change-Id: I7a0fffc97e1bf08f5723f4397dd7607e9d2264f8
Signed-off-by: Can Guo <cang@codeaurora.org>