[Bugfix] Fix multi nodes TP+PP for XPU (#8884)

Signed-off-by: YiSheng5 <syhm@mail.ustc.edu.cn>
Signed-off-by: yan ma <yan.ma@intel.com>
Co-authored-by: YiSheng5 <syhm@mail.ustc.edu.cn>

vllm/platforms/xpu.py

@@ -20,3 +20,7 @@ class XPUPlatform(Platform):
     def get_device_total_memory(cls, device_id: int = 0) -> int:
         device_props = torch.xpu.get_device_properties(device_id)
         return device_props.total_memory
+
+    @staticmethod
+    def inference_mode():
+        return torch.no_grad()