Set default helicity reversal frequency to 120 Hz.

  Now for 30 Hz, need to override in parameter file

src/THcHelicity.cxx

@@ -126,7 +126,8 @@ Int_t THcHelicity::ReadDatabase( const TDatime& date )
   fRingSeed_reported_initial = 0; // Initial see that should predict reported
                                 // helicity of first quartet.
   fFirstCycle = -1; // First Cycle that starts a quad (0 to 3)
-  fFreq = 29.5596;
+#  fFreq = 29.5596;
+  fFreq = 120.0007547169;
   fHelDelay=8;
 
   DBRequest list[]= {