CCodecBufferChannel: Resolve race condition around mComponent

mComponent may be accessed from SurfaceListener after
CCodecBufferChannel::release() being called.
Handle the race condition of mComponent regarding std::shared_ptr, by
using atomic access.

Flag: EXEMPT bugfix
Bug: 356734093
Test: presubmit
Change-Id: Id2cb7e5455e281e58814e4b6ab3582678c161539