ARM: dts: msm: Add VDD_CX to Dragonboard APQ8074 camera

While camera preview or recording is in progress,
there are plenty of opportunities for CX to run
in auto mode. However, since these use cases
have relatively high load, running in auto mode
may have an adverse effect on stability. Therefore,
disable auto mode on MSM8974 while the camera is
in use.

Change-Id: I828cdcb99f7ee44d3d8d330e060093fcf3c2e621
Signed-off-by: Ilia Lin <ilialin@codeaurora.org>