v4l2codecs: Rework handling of queues and pending requests
Starting from this patch, all queue and dequeue operation happening on V4L2 is now abstracted with the request. Buffers are dequeued automatically when pending requests are marked done and only 1 in-flight request is not used.
Along with fixing issues with request not being reused with slice decoders, this change reduces the memory footprint by allocating only two bitstream buffers.
Depends on !1925 (merged) cc @seungha.yang
Edited by Nicolas Dufresne