bugfix: fix initialization error for mooncake in k8s (#2541)

### What this PR does / why we need it?
The detail has been clarified in that issue :
https://github.com/vllm-project/vllm-ascend/issues/2557

### Does this PR introduce _any_ user-facing change?
NO

### How was this patch tested?
easy to test beacause we just need to echo the variable


- vLLM version: v0.10.1.1
- vLLM main:
6997a25ac6

---------

Signed-off-by: zzy-ContiLearn <1831242919@qq.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: LCAIZJ <leichao139636@163.com>

examples/disaggregated_prefill_v1/mooncake_connector_deployment_guide.md

@@ -32,6 +32,7 @@ export GLOO_SOCKET_IFNAME="xxxxxx"
 export TP_SOCKET_IFNAME="xxxxxx"
 export HCCL_SOCKET_IFNAME="xxxxxx"
 export ASCEND_RT_VISIBLE_DEVICES=0,1,2,3
+export PHYSICAL_DEVICES=$(ls /dev/davinci* 2>/dev/null | grep -o '[0-9]\+' | sort -n | paste -sd',' -)
 
 vllm serve "/xxxxx/DeepSeek-V2-Lite-Chat" \
   --host localhost \
@@ -100,6 +101,7 @@ export GLOO_SOCKET_IFNAME="xxxxxx"
 export TP_SOCKET_IFNAME="xxxxxx"
 export HCCL_SOCKET_IFNAME="xxxxxx"
 export ASCEND_RT_VISIBLE_DEVICES=4,5,6,7
+export PHYSICAL_DEVICES=$(ls /dev/davinci* 2>/dev/null | grep -o '[0-9]\+' | sort -n | paste -sd',' -)
 
 vllm serve "/xxxxx/DeepSeek-V2-Lite-Chat" \
   --host localhost \