QML UI: Remove unused onClicked event for back button

I don't know how this got here.  Probably having fun
with copy and paste.

Signed-off-by: Henrik Brautaset Aronsen <subsurface@henrik.synth.no>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-mobile/qml/TopBar.qml

@@ -100,13 +100,6 @@ Rectangle {
 				width: Math.round(MobileComponents.Units.gridUnit * 1.7)
 				height: width
 			}
-			MouseArea {
-				height: parent.height
-				width: parent.width
-				onClicked: {
-					detailsWindow.open()
-				}
-			}
 			MouseArea {
 				height: parent.height
 				width: parent.width