WMF: fixed QMediaPlayer changing to EndOfMedia status too early.

WMF: fixed QMediaPlayer changing to EndOfMedia status too early.

It was changing to EndOfMedia status and explicitly stopping playback
when receiving the MEEndOfPresentation event from the WMF session.
However, this event means that all data has bean read from the source but
not necessarily played yet. According to the documentation, playback is
done when the MESessionEnded event is sent. It now reports the EndOfMedia
status at that moment instead. stop() is not explicitly called anymore since
MESessionEnded also implies the session has stopped.

Task-number: QTBUG-30825
Change-Id: I6c6c09e736fe33f7cf17c75038ea7be1b5701a1c
Reviewed-by: Christian Stromme <christian.stromme@digia.com>