PlayerControlTv: Fix don't wait buffering done.
PlayerControlTv: Fix don't wait buffering done.

When pipeline is in buffering, activate_player_control() may set
pipeline to playing, so that pipeline will always stay in starvation.

MCherifiOSS/umms,MCherifiOSS/umms,MCherifiOSS/umms,MCherifiOSS/umms