Reduce duplicates of channel struct

Add/Fix custom clock limit defines (for YMF278B)

src/engine/platform/bubsyswsg.h

@@ -27,10 +27,8 @@
 #include "vgsound_emu/src/k005289/k005289.hpp"
 
 class DivPlatformBubSysWSG: public DivDispatch {
-  struct Channel {
-    int freq, baseFreq, pitch, pitch2, note, ins;
-    bool active, insChanged, freqChanged, keyOn, keyOff, inPorta;
-    signed char vol, outVol, wave;
+  struct Channel: public SharedChannelFreq, public SharedChannelVolume<signed char> {
+    signed short wave;
     signed char waveROM[32] = {0}; // 4 bit PROM per channel on bubble system
     DivMacroInt std;
     DivWaveSynth ws;
@@ -39,20 +37,8 @@ class DivPlatformBubSysWSG: public DivDispatch {
       pitch2=0;
     }
     Channel():
-      freq(0),
-      baseFreq(0),
-      pitch(0),
-      pitch2(0),
-      note(0),
-      ins(-1),
-      active(false),
-      insChanged(true),
-      freqChanged(false),
-      keyOn(false),
-      keyOff(false),
-      inPorta(false),
-      vol(15),
-      outVol(15),
+      SharedChannelFreq(),
+      SharedChannelVolume<signed char>(15),
       wave(-1) {}
   };
   Channel chan[2];