Drop the V1 plugin API compatibility code

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

src/Kaleidoscope/HostOS-Base.cpp

@@ -71,12 +71,5 @@ bool Base::focusHook(const char *command) {
   return true;
 }
 
-// Legacy V1 API
-#if KALEIDOSCOPE_ENABLE_V1_PLUGIN_API
-void Base::begin() {
-  ::HostOS.onSetup();
-}
-#endif
-
 }
 }

src/Kaleidoscope/HostOS-Base.h

@@ -45,10 +45,6 @@ class Base : public kaleidoscope::Plugin {
   virtual void autoDetect(void) {}
   Type os_;
 
-#if KALEIDOSCOPE_ENABLE_V1_PLUGIN_API
-  void begin();
-#endif
-
  private:
   uint16_t eeprom_slice_;
   bool is_configured_ = false;