The test case shown in [1] triggers the kernel to access the null pointer.
Therefore, add related test cases to mq.
The test results are as follows:

./tdc.py -e 0531
1..1
ok 1 0531 - Replace mq with invalid parent ID

./tdc.py -c mq
1..8
ok 1 ce7d - Add mq Qdisc to multi-queue device (4 queues)
ok 2 2f82 - Add mq Qdisc to multi-queue device (256 queues)
ok 3 c525 - Add duplicate mq Qdisc
ok 4 128a - Delete nonexistent mq Qdisc
ok 5 03a9 - Delete mq Qdisc twice
ok 6 be0f - Add mq Qdisc to single-queue device
ok 7 1023 - Show mq class
ok 8 0531 - Replace mq with invalid parent ID

[1] https://lore.kernel.org/all/20230527093747.3583502-1-shaozhengchao@huawei.com/Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Reviewed-by: Pedro Tammela <pctammela@mojatatu.com>
Link: https://lore.kernel.org/r/20230601012250.52738-1-shaozhengchao@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>