remove the duplicate method `is_private_use1` in class Device (#107198)
In the `Device` class, there are two methods with similar functions called `is_private_use1` and `is_privateuseone`.
https://github.com/pytorch/pytorch/blob/ddf36c82b83b2db3be7ce7a85d4aea3507c9d7ef/c10/core/Device.h#L84-L87
https://github.com/pytorch/pytorch/blob/ddf36c82b83b2db3be7ce7a85d4aea3507c9d7ef/c10/core/Device.h#L159-L162
The former is not being utilized and therefore, this PR removes it.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/107198
Approved by: https://github.com/bdhirsh
