Remove amp() from abstract accelerator (#7879)
Pytorch now provide torch.amp
https://docs.pytorch.org/docs/stable/amp.html as recommended AMP API
instead of torch.<device_type>.amp which is used in DeepSpeed abstract
accelerator amp(). Some PyTorch backend such as XPU does not provide the
legacy `torch.xpu.amp` module.
This PR replace `get_accelerator().amp()` by `torch.amp` which is the
recommended way of using AMP.
Related issues and PRs
https://github.com/deepspeedai/DeepSpeed/issues/7876
https://github.com/deepspeedai/DeepSpeed/pull/7877
---------
Signed-off-by: Ma, Guokai <guokai.ma@intel.com>
Co-authored-by: Olatunji Ruwase <tjruwase@gmail.com>
