DiscIO: Remove C/I/S prefixes from class names

These prefixes were inconsistent with the rest of Dolphin.

I'm also renaming VolumeWiiCrypted to VolumeWii because of 1113b13.

Source/Core/UICommon/WiiUtils.cpp

@@ -58,7 +58,7 @@ bool InstallWAD(const std::string& wad_path)
     return false;
   }
 
-  DiscIO::CNANDContentManager::Access().ClearCache();
+  DiscIO::NANDContentManager::Access().ClearCache();
   return true;
 }
 }