RTSP: RTSP streaming aborted by packet loss.

[Problem] RTSP streaming aborted right after resume.
[Cause] RTSP aborted because sequence number jumped
  more than kMaxAllowedStaleAccessUnits(20) defined
[Solution]
  For a voice session, about 20 packets are represents
  about 20 frames.
  For a video session, about 20 packets are represents
  only few frames(or one frame).
  Aborting a rtp session by 20 packet lost is too tight
  condition for video session.
  So that, adjusts it to 400 packets.

Bug: 193115006

Signed-off-by: Byeongjo Park <bjo.park@samsung.com>
Merged-in: If3b4703a4891ce183c02d815f8e0647b8a1b792b
Change-Id: If3b4703a4891ce183c02d815f8e0647b8a1b792b