[mlir][test] Fix -Wformat in sparse_tensor.c (NFC)

llvm-project/mlir/test/CAPI/sparse_tensor.c:50:43:
error: format specifies type 'unsigned long long' but the argument has type 'MlirSparseTensorLevelType' (aka 'unsigned long') [-Werror,-Wformat]
    fprintf(stderr, "level_type: %llu\n", lvlTypes[l]);
                                 ~~~~     ^~~~~~~~~~~
                                 %lu
1 error generated.