ARM: dts: msm: Add linux,contiguous-region for 8939 PIL regions

PIL is now being migrated from Ion to using CMA
regions. Add the phandle reference to the CMA
regions. Also remove venus area from memory
layout thus reducing the peripheral_region by 5MB
and create a separate CMA region to serve video
needs.

Change-Id: I9c8f2753af8b04f055768fc86f584f6d17e52c56
Signed-off-by: Susheel Khiani <skhiani@codeaurora.org>