msm: vidc: Align release buffers with V4L2 states

Instead of releasing the buffers in buffer requirements call,
release them in buf_cleanup callback which exactly intended
for this purpose.

CRs-Fixed: 1092644
Change-Id: Ieb6462ee6a3e4f29d8e620cce92eb5f05d347c29
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>