[Misc] Fix C++ comment style. (#5467)

Co-authored-by: Ubuntu <ubuntu@ip-172-31-28-63.ap-northeast-1.compute.internal>

include/dgl/aten/coo.h

@@ -232,8 +232,10 @@ std::pair<bool, bool> COOIsSorted(COOMatrix coo);
 std::vector<runtime::NDArray> COOGetDataAndIndices(
     COOMatrix mat, runtime::NDArray rows, runtime::NDArray cols);
 
-/** @brief Get data. The return type is an ndarray due to possible duplicate
- * entries. */
+/**
+ * @brief Get data. The return type is an ndarray due to possible duplicate
+ * entries.
+ */
 inline runtime::NDArray COOGetAllData(COOMatrix mat, int64_t row, int64_t col) {
   IdArray rows =
       VecToIdArray<int64_t>({row}, mat.row->dtype.bits, mat.row->ctx);