Upgrading TFAutoModelWithLMHead to (#7730)
Upgrading TFAutoModelWithLMHead to (#7730)

- TFAutoModelForCausalLM
- TFAutoModelForMaskedLM
- TFAutoModelForSeq2SeqLM

as per deprecation warning. No tests as it simply removes current
warnings from tests.
huggingface/transformers,huggingface/transformers,huggingface/transformers,huggingface/pytorch-transformers,huggingface/transformers