RetroAchievements - Close game on switch to null hash

Mistakenly thought the change media call would close the current
game if the new media failed to hash. This wasn't the case so
instead I'll close the current game myself. This fixes an issue
where a default ISO would immediately load achievements when
starting up the Wii menu.

Source/Core/Core/AchievementManager.cpp

@@ -167,7 +167,7 @@ void AchievementManager::LoadGame(const DiscIO::Volume* volume)
     WARN_LOG_FMT(ACHIEVEMENTS, "Software format unsupported by AchievementManager.");
     if (rc_client_get_game_info(m_client))
     {
-      rc_client_begin_change_media_from_hash(m_client, "", ChangeMediaCallback, NULL);
+      CloseGame();
     }
     else
     {