QML UI: explicitly reference parent id

Otherwise we get an odd 'TypeError: Cannot read property of null'
error message.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

mobile-widgets/qml/Log.qml

@@ -28,7 +28,7 @@ Kirigami.ScrollablePage {
 			text: qsTr("Application Log")
 		}
 		delegate : Text {
-			width: parent.width
+			width: logWindow.width
 			wrapMode: Text.WrapAtWordBoundaryOrAnywhere
 			text : message
 		}