ARM: dts: msm: add device tree overlay support for sdm450/sdm632

Sdm450 and sdm632 shared the same mtp, cdp, qrd
board design. Add base device tree overlay support
for such sdm450/sdm632 variant boards.

Change-Id: I0925df5a028c43f125e39f6959764af3abb8cc14
Signed-off-by: Maria Yu <aiquny@codeaurora.org>