msm: vidc: Free memory allocated to keep track of buffer ownership

Memory for free_output_indices and free_input_indices was never freed.
This commit kfrees the memory as part of venc_close().

CRs-Fixed: 631998
Change-Id: Iae28a1266bdf78445c1a936721d9901c9fa0f285
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>