WiimoteDevice: Make Callback_WiimoteInterruptChannel() accept its data as a u8* rather than void*

All current usages of the function pass in either u8 arrays or pointers,
so we can make this part of the function a concrete type.

Source/Core/Core/Core.h

@@ -59,7 +59,7 @@ State GetState();
 void SaveScreenShot(bool wait_for_completion = false);
 void SaveScreenShot(const std::string& name, bool wait_for_completion = false);
 
-void Callback_WiimoteInterruptChannel(int _number, u16 _channelID, const void* _pData, u32 _Size);
+void Callback_WiimoteInterruptChannel(int number, u16 channel_id, const u8* data, u32 size);
 
 // This displays messages in a user-visible way.
 void DisplayMessage(const std::string& message, int time_in_ms);