Remove unnecessary import statement in QML snippet

Change-Id: I1f34e52c4a8f72a91b1c673fe7e152335d8a0ade
Reviewed-by: Venugopal Shivashankar <Venugopal.Shivashankar@qt.io>

src/imports/multimedia/qdeclarativeplaylist.cpp

@@ -88,9 +88,6 @@ void QDeclarativePlaylistItem::setSource(const QUrl &source)
     item's source URL can be accessed using the \c source role.
 
     \qml
-    import QtQuick 2.0
-    import QtMultimedia 5.6
-
     Item {
         width: 400;
         height: 300;