Remove `MarkupLMForMaskedLM` from `MODEL_WITH_LM_HEAD_MAPPING_NAMES` (#19534)

Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>

src/transformers/models/auto/modeling_auto.py

@@ -253,7 +253,6 @@ MODEL_WITH_LM_HEAD_MAPPING_NAMES = OrderedDict(
         ("luke", "LukeForMaskedLM"),
         ("m2m_100", "M2M100ForConditionalGeneration"),
         ("marian", "MarianMTModel"),
-        ("markuplm", "MarkupLMForMaskedLM"),
         ("megatron-bert", "MegatronBertForCausalLM"),
         ("mobilebert", "MobileBertForMaskedLM"),
         ("mpnet", "MPNetForMaskedLM"),