Double counts in parameter count

Currently, parameter counts in `utils.get_parameters_in_billions` are inaccurate when PP > 1. Tied variables, in particular embedding layers, exist in several copies in the first and last PP stage, which causes double counts. For now the codebase only uses the count without embedding layers which is accurate, but it would be good for the count with embedding layers to also function, mostly for operation-counting.

For background see: https://github.com/bigscience-workshop/Megatron-DeepSpeed/pull/40