[MM][Bugfix] Update hf_config to hf_text_config (#5319)

### What this PR does / why we need it?

Following https://github.com/vllm-project/vllm-ascend/pull/5205, update
`hf_config` to `hf_text_config`.

Find more details at
https://github.com/vllm-project/vllm-ascend/pull/5205#issuecomment-3675417534
and
https://github.com/vllm-project/vllm-ascend/pull/5205#issuecomment-3677920872.

### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

- vLLM version: release/v0.13.0
- vLLM main:
5fbfa8d9ef

Signed-off-by: shen-shanshan <467638484@qq.com>

tests/ut/spec_decode/test_mtp_proposer.py

@@ -41,7 +41,7 @@ class TestMtpProposer:
         config.model_config.dtype = torch.float16
         config.model_config.max_model_len = 2048
         config.model_config.uses_mrope = False
-        config.model_config.hf_config = None
+        config.model_config.hf_text_config = None
 
         config.load_config = None