qt: fix QtQuick version

Connections.enabled requires QtQuick 2.7:

    qml: component is not ready: qrc:/player/Player.qml:121 Type PlayerPlaylistVisiblityFSM unavailable
    qrc:/player/PlayerPlaylistVisiblityFSM.qml:99 "Connections.enabled" is not available in QtQuick 2.0.

For consistency with other Qml headers, use QtQuick 2.11.

Refs https://phabricator.kde.org/D14984

modules/gui/qt/player/qml/PlayerPlaylistVisiblityFSM.qml

@@ -15,7 +15,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  *****************************************************************************/
-import QtQuick 2.0
+import QtQuick 2.11
 import org.videolan.vlc 0.1
 
 /**