flowchart: hide mirrored negative spectrum in frequency plot

scope.grc

@@ -269,7 +269,7 @@ blocks:
     ctrlpanel: 'False'
     fc: '0'
     fftsize: '1024'
-    freqhalf: 'True'
+    freqhalf: 'False'
     grid: 'False'
     gui_hint: ''
     label: Relative Gain