msm: ocmem: Add zone initialization checks

Since OCMEM zones can vary based on the target
add an initialization flag for each zone.

Also restrict each client to only operate on
active zones.

Change-Id: Iccac64fea277f833034ddfe71cce084060cfa16d
Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>