staging: vc04_services: codec: Fix incorrect buffer cleanup

staging: vc04_services: codec: Fix incorrect buffer cleanup

The allocated input and output buffers are initialised in
buf_init and should only be cleared up in buf_cleanup.
stop_streaming was (incorrectly) cleaning up the buffers to
avoid an issue in videobuf2 that had been fixed by the orphaned
buffer support.

Remove the erroneous cleanup.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
[sw0312.kim: cherry-pick rpi-5.4.y commit to fix video decoding seek issue]
Ref: https://github.com/raspberrypi/linux/pull/3790
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I38e3a257a941753b02e448d6d5dd1c8486b648f1