fix typo preventing `ipython qtconsole --style` from having effect

IPython/frontend/qt/console/qtconsoleapp.py

@@ -503,7 +503,7 b' class IPythonQtConsoleApp(BaseIPythonApplication):'
         except AttributeError:
             colors = None
         try:
-            style = self.config.IPythonWidget.colors
+            style = self.config.IPythonWidget.syntax_style
         except AttributeError:
             style = None