move to cpu (#5187)

Co-authored-by: Steve <ubuntu@ip-172-31-34-29.ap-northeast-1.compute.internal>

notebooks/sparse/quickstart.ipynb

@@ -329,7 +329,7 @@
         "val = torch.tensor([1., 2., 3., 4.])\n",
         "A = dglsp.from_coo(row, col, val)\n",
         "\n",
-        "B = A.to(device='cuda:0', dtype=torch.int32)\n",
+        "B = A.to(device='cpu', dtype=torch.int32)\n",
         "print(f\"Device sparse matrix is stored on: {B.device}\")\n",
         "print(f\"Datatype of sparse matrix: {B.dtype}\")"
       ],