[Refact.]: Refactor some leftover implementations of 300I DUO in the main branch. (#6425)

### What this PR does / why we need it?
- Replace the RoPE operator implementation.
- Refactor some leftover implementations of 300I DUO in the main branch.

### Does this PR introduce _any_ user-facing change?
NA
### How was this patch tested?

- vLLM version: v0.14.1
- vLLM main:
dc917cceb8

---------

Signed-off-by: Tflowers-0129 <2906339855@qq.com>

vllm_ascend/_310p/ops/mm_encoder_attention.py

@@ -19,10 +19,10 @@ import einops
 import torch
 import torch_npu
 
-from vllm_ascend.ops.mm_encoder_attention import AscendMMEncoderAttention as _Base
+from vllm_ascend.ops.mm_encoder_attention import AscendMMEncoderAttention
 
 
-class AscendMMEncoderAttention310(_Base):
+class AscendMMEncoderAttention310(AscendMMEncoderAttention):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)