Add index to HPU devices (#7497)
The [PR #7266](https://github.com/deepspeedai/DeepSpeed/pull/7266)
enforces the devices having explicit device indices (i.e. 'hpu:0',
'cuda:0', etc).
This PR aligns HPU devices to the requirement.
Signed-off-by: Max Kovalenko <mkovalenko@habana.ai>
