[XPU] Fix compile_size is None case. (vllm-project#25433)

Signed-off-by: Kunshang Ji <kunshang.ji@intel.com>

Author: jikunshang

vllm/platforms/xpu.py

@@ -113,6 +113,8 @@ def check_and_update_config(cls, vllm_config: VllmConfig) -> None:
         # lazy import to avoid circular import
         from vllm.config import CompilationLevel, CUDAGraphMode
         compilation_config = vllm_config.compilation_config
+        if compilation_config.compile_sizes is None:
+            compilation_config.compile_sizes = []
 
         assert compilation_config.cudagraph_mode == CUDAGraphMode.NONE, \
             "CUDA graph mode should be NONE on XPU"