Fix sgl_kernel import failure on devices other than CUDA (#10610)

docs/platforms/cpu_server.md

@@ -63,7 +63,7 @@ is required to enable SGLang service with CPU engine.
 conda create -n sgl-cpu python=3.12 -y
 conda activate sgl-cpu
 
-# Optional: Set PyTorch CPU as primary pip install channel to avoid installing CUDA version
+# Set PyTorch CPU as primary pip install channel to avoid installing the larger CUDA-enabled version and prevent potential runtime issues.
 pip config set global.index-url https://download.pytorch.org/whl/cpu
 pip config set global.extra-index-url https://pypi.org/simple
 

sgl-kernel/python/sgl_kernel/__init__.py

@@ -23,7 +23,7 @@ def _find_cuda_home():
     return cuda_home
 
 
-if torch.version.hip is None:
+if torch.version.cuda is not None:
     cuda_home = Path(_find_cuda_home())
 
     if (cuda_home / "lib").is_dir():