Fix Meta Tensor checkpoint load for OPT models

[lekurile]

This PR fixes Meta Tensor checkpoint loading for OPT models where the SD keys start with model..

Command:

deepspeed --num_nodes 1 --num_gpus 1 inference-test.py --ds_inference --use_kernel --name <model_name> --use_meta_tensor --dtype <model_dtype>

Model table:

OPT Model	SD Key	Before Fix	After Fix
facebook/opt-125m	model.decoder.embed_tokens.weight	FAIL	PASS
facebook/opt-350m	decoder.embed_tokens.weight	PASS	PASS
facebook/opt-1.3b	model.decoder.embed_tokens.weight	FAIL	PASS
facebook/opt-2.7b	model.decoder.embed_tokens.weight	FAIL	PASS
facebook/opt-6.7b	decoder.layers.23.fc2.weight	PASS	PASS
facebook/opt-13b	decoder.embed_tokens.weight	PASS	PASS
facebook/opt-30b	decoder.layers.31.fc1.weight	PASS	PASS