RTSP: Fix crash issue while repeated pause/resume

While doing repeated pause-resume operation in RTSP streaming,
some times, the accessunit timeout check is being posted when
the streaming paused, and even after receving the EOS.
Due to this check, after the EOS, the number of packets received
will be zero and the session gets Teardown while the
streaming is paused. Upon resume, it leads to check failure and crash.

Changes are done such that the accessunit timeout check will
not be done in pause/seek state.

CRs-Fixed: 636312

Change-Id: I60d09d5394eed59a8e2bbf5556628f1ea26f7807