AM demod: fixed initialization of squelch counter. Fixes issue #502

plugins/channelrx/demodam/amdemodsink.cpp

@@ -29,6 +29,7 @@
 AMDemodSink::AMDemodSink() :
         m_channelSampleRate(48000),
         m_channelFrequencyOffset(0),
+        m_squelchCount(0),
         m_squelchOpen(false),
         m_squelchDelayLine(9600),
         m_magsqSum(0.0f),