[bloom] fix alibi device placement
This PR fixes alibi device placement - currently it's the default device which breaks things at times - it has to be set explicitly to the correct device.

The problem emerged when trying to get DeepSpeed-Inference working.

Kudos to @RezaYazdaniAminabadi for discovering the problem.

cc: @younesbelkada 


_The documentation is not available anymore as the PR was closed or merged._<|||||>Thanks a lot for the fix !<|||||>btw, we also discussed to change the alibi creation logic.

it should create it once in init with a largish length (say 1k) and not change it again unless the input is longer.  

then the device and dtype will be automatically handled correctly.

this is the logic that all `transformers` positional embeddings use.<|||||>Yes agreed !
We are already addressing these issues in this PR together with refactoring the whole attention block which looks too complicated : https://github.com/huggingface/transformers/pull/17866 
Here alibi (including the shifting) and the attention mask is created only once 