modais: Initialize remaining AISModSource members

Cppcheck reported several AISModSource members that were not initialized
by the constructor. Initialize the remaining scalar members in the
constructor initializer list to establish a well-defined initial state
and avoid undefined behavior if they are accessed before being assigned.

Reported by cppcheck.

Signed-off-by: Robin Getz <rgetz503@gmail.com>

plugins/channeltx/modais/aismodsource.cpp

@@ -35,9 +35,16 @@ AISModSource::AISModSource() :
     m_scopeSink(nullptr),
     m_magsq(0.0),
     m_levelCalcCount(0),
+    m_rmsLevel(0.0),
+    m_peakLevelOut(0.0),
     m_peakLevel(0.0f),
     m_levelSum(0.0f),
+    m_sampleIdx(0),
+    m_pow(0.0f),
+    m_powRamp(0.0f),
     m_state(idle),
+    m_waitCounter(0),
+    m_nrziBit(0),
     m_byteIdx(0),
     m_bitIdx(0),
     m_last5Bits(0),