renderer_vulkan: add locks to avoid scheduler flushes from CPU

src/video_core/fence_manager.h

@@ -86,7 +86,10 @@ public:
             uncommitted_operations.emplace_back(std::move(func));
         }
         pending_operations.emplace_back(std::move(uncommitted_operations));
-        QueueFence(new_fence);
+        {
+            std::scoped_lock lock{buffer_cache.mutex, texture_cache.mutex};
+            QueueFence(new_fence);
+        }
         if (!delay_fence) {
             func();
         }