[EPLB][Bugfix] Dispatch Allgather use log2phy if enable eplb (#5933)

### What this PR does / why we need it?
1. Move the logic of expert mapping forward to prevent shotgun changes
2. Disable the update of expert map.

### How was this patch tested?
a2
| dataset | version | metric | mode | vllm-api-general-chat |
|----- | ----- | ----- | ----- | -----|
| GPQA_diamond | 53064e | accuracy | gen | 73.23 |

a3
| dataset | version | metric | mode | vllm-api-general-chat |
|----- | ----- | ----- | ----- | -----|
| aime2024 | 604a78 | accuracy | gen | 83.33 |


- vLLM version: v0.13.0
- vLLM main:
11b6af5280

Signed-off-by: shenchuxiaofugui <1311027364@qq.com>

vllm_ascend/eplb/eplb_updator.py

@@ -38,7 +38,6 @@ class EplbUpdator:
     def set_adaptor(self, adaptor):
         self.adaptor = adaptor
         self.num_moe_layers = self.adaptor.num_moe_layers
-        self.global_expert_num = self.adaptor.global_expert_num
 
     def init_eplb(self, expert_map_path, process):
         self.rank_id = dist.get_rank()