Update modeling_mpt.py

remove one line of import to evade a bug of bloom model

modeling_mpt.py

@@ -20,7 +20,7 @@ from .ffn import build_ffn as build_ffn
 from .norm import NORM_CLASS_REGISTRY
 from .configuration_mpt import MPTConfig
 from .adapt_tokenizer import AutoTokenizerForMOD, adapt_tokenizer_for_denoising
-from .hf_prefixlm_converter import add_bidirectional_mask_if_missing, convert_hf_causal_lm_to_prefix_lm
+# from .hf_prefixlm_converter import add_bidirectional_mask_if_missing, convert_hf_causal_lm_to_prefix_lm
 from .meta_init_context import init_empty_weights
 from .param_init_fns import generic_param_init_fn_, MODEL_INIT_REGISTRY
 try: