ARM: dts: msm: Add linux,contiguous-region for 8916 PIL regions

PIL is now being migrated from Ion to using CMA regions. Add the phandle
reference to the CMA regions for later use. This has no effect until
dma_alloc is called.

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: Icb1cb42bf41508a37892223a61da18598f7c8558
Signed-off-by: Shiraz Hashim <shashim@codeaurora.org>