msm: camera: Memory allocation using cma

For large contiguous memory allocations cma_alloc is
to be used over kzalloc to avoid higher order page
allocation failures.

Change-Id: Iedb2ce8e6e7a9bf936f3f1b5bdbd2634ad25697c
Signed-off-by: Karthik Anantha Ram <kartanan@codeaurora.org>