free_cv is no longer in use

src/video_core/renderer_vulkan/vk_master_semaphore.h

@@ -78,7 +78,6 @@ private:
     std::atomic<u64> notify_counter{0}; ///< Fence completion counter for atomic wait.
     std::mutex wait_mutex;
     std::mutex free_mutex;
-    std::condition_variable free_cv;
     std::condition_variable_any wait_cv;
     std::queue<Waitable> wait_queue;  ///< Queue for the fences to be waited on by the wait thread.
     std::deque<vk::Fence> free_queue; ///< Holds available fences for submission.