vulkan: improve partial offloading performance on AMD (ggml-org#19976)

* vulkan: fix and enable cpy_tensor_async function

* use transfer_queue for async transfers on AMD, synchronize with timeline semaphore

* update offload_op logic

* fix missing transfer submission

* disable async transfer queue on AMD GCN

* revert op batch size change

* fix cpy_tensor_async checks

Author: 0cc4m