msm: vidc: Remove prepare and release buf implementation

After moving to Dynamic buffers mode, Venus HW doesn't need to
know about Input and Output buffers ahead. It can handle any new
buffer runtime. Hence remove prepare buf and associated release
buf implementation.

CRs-Fixed: 2012385
Change-Id: I313669447bb39b19292514a6ed2ffd450c7e992c
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>