msm: ocmem: Add support for dumping OCMEM

Allow the OCMEM clients to obtain a copy of their
allocations in OCMEM by using the dump API. The clients
can then merge this copy as a part of other client areas
in their ramdumps.

Change-Id: Ib9772062cd60772ac98e7c4ce798032c574185da
Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>