msm: vidc: Free OCMEM during power collapse

To disable OCMEM clock during power collapse, video driver
has to free up the allocated OCMEM. This memory will be
re-allocated before bringing venus core out of reset.

CRs-Fixed: 604629
Change-Id: I88f7e771b21046d9817feb17b06b3739f128c434
Signed-off-by: Vikash Garodia <vgarodia@codeaurora.org>