NuPlayer: Fix ANR while resetting RTSP playback

- When network is poor, the response of RTSP teardown won't be received
  in time, so ANR will happen.
- With this patch, a teardown message will be sent when timeout expires,
  in order to avoid ANR.

Change-Id: I3f9efd9fefa66104ad452559ced5ff5218d73a66
CRs-Fixed: 650866