ARM: dts: msm: Describe reserved-memory regions for sdm640

Add carveout memory regions, based on memory map v3, as well as
for CMA and other contiguous memory usecases for sdm640.

Change-Id: I267c72c45439d356a5f9a248330d6e29bd86189d
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>