TestSink: removed useless code

plugins/samplesink/testsink/testsinkgui.cpp

@@ -266,7 +266,6 @@ void TestSinkGui::on_interp_currentIndexChanged(int index)
 
     m_settings.m_log2Interp = index;
     ui->glSpectrum->setSampleRate(m_settings.m_sampleRate*(1<<m_settings.m_log2Interp));
-    updateSampleRateAndFrequency();
     sendSettings();
 }