refactor: Support user supplied SM count for NVIDIA GPUs

[mahendrapaipuri]

• For NVIDIA GPUs, SM count depends on the form factor even for the same GPU model. It is not easy to keep list of all SMs and even if we managed to do it, the way NVIDIA exposes the model name is not standardised, so there is no easy way to map the models to SM count. So, we delegate this task to operators where they can supply SM count for each GPU using CLI argument. When MIG is enabled and this CLI argument is not provided, we emit a warning log so that operators will know that we are using default SM count for current GPUs