Update real_accelerator.py (#6845)
### Comment out or delete `accelerate_name="cpu"` when `xpu` is not
detected.
When `xpu `is not detected it just pass at lines from 68 to 74 if
`DS_ACCELERATOR` is set. However, `cpu` is assigned to `accelerate_name`
if it cannot import `intel_extension_for_pytorch` or find` xpu`, namely,
at line from 125 to 133 when`DS_ACCELERATOR` is not set.
I found this problem yesterday and spent whole afternoon figuring it
out. I got `intel_extension_for_pytorch `installed with other package
which I do not use actually and have no idea about this. Then I found
that it `cpu` is assigned to accelerate_name directly if it cannot find
`xpu` and it affects `cuda` detection. In fact, `cpu` will be assigned
finally if `cuda` is even not detected at line from 170 to 177.
---------
Co-authored-by: Olatunji Ruwase <olruwase@microsoft.com>
Co-authored-by: Logan Adams <loadams@microsoft.com>
Co-authored-by: Logan Adams <114770087+loadams@users.noreply.github.com>
