[Bugfix] Fix custom op register issue (#2409)

### What this PR does / why we need it?
Our current code register the custom ops inside the platform
intialization phase. however, when a new process started by creating a
worker, the former patch will lose it effect on the custom ops and lead
to fallback to the native pass wrote in vllm. This PR move the patch
code to the worker to make sure the custom op patch worker as our
expected.

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

- vLLM version: v0.10.0
- vLLM main:
8ea0c2753a

Signed-off-by: ganyi <pleaplusone.gy@gmail.com>

vllm_ascend/platform.py

@@ -29,7 +29,7 @@ from vllm.platforms import Platform, PlatformEnum
 from vllm_ascend.ascend_config import (check_ascend_config, get_ascend_config,
                                        init_ascend_config)
 from vllm_ascend.utils import (ASCEND_QUATIZATION_METHOD, is_310p,
-                               register_ascend_customop, update_aclgraph_sizes)
+                               update_aclgraph_sizes)
 
 if TYPE_CHECKING:
     from vllm.config import ModelConfig, VllmConfig
@@ -201,9 +201,6 @@ class NPUPlatform(Platform):
                     "For better performance in Qwen3 MoE, SP only works exclusively with MC2, AllToAll, and AllToAllV."
                 )
 
-        # register Ascend CustomOp
-        register_ascend_customop()
-
     @classmethod
     def get_attn_backend_cls(cls,
                              selected_backend,