pytorch

50c972bf - [c10d] Add xpu to the default device supported by user specified backend (#103410)

[c10d] Add xpu to the default device supported by user specified backend (#103410) **Motivation:** For collective dispatching, we want to provide a more user friendly usage for xpu device and CCL backend (user specified backend) mapping. **Solution:** We add xpu to the default device list, and it can construct the mapping between xpu and the user specified backend directly. Usage: When using xpu device, user can specify backend name only: `dist.init_process_group(backend='ccl')` Pull Request resolved: https://github.com/pytorch/pytorch/pull/103410 Approved by: https://github.com/jgong5, https://github.com/ezyang