selftests/tc-testing: replace mq with invalid parent ID

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.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/tc-testing/tc-tests/qdiscs/mq.json

@@ -155,5 +155,28 @@
             "teardown": [
                 "echo \"1\" > /sys/bus/netdevsim/del_device"
             ]
-        }
+	},
+	{
+		"id": "0531",
+		"name": "Replace mq with invalid parent ID",
+		"category": [
+			"qdisc",
+			"mq"
+		],
+		"plugins": {
+			"requires": "nsPlugin"
+		},
+		"setup": [
+			"echo \"1 1 16\" > /sys/bus/netdevsim/new_device",
+			"$TC qdisc add dev $ETH root handle ffff: mq"
+		],
+		"cmdUnderTest": "$TC qdisc replace dev $ETH parent ffff:fff1 handle ffff: mq",
+		"expExitCode": "2",
+		"verifyCmd": "$TC qdisc show dev $ETH",
+		"matchPattern": "qdisc [a-zA-Z0-9_]+ 0: parent ffff",
+		"matchCount": "16",
+		"teardown": [
+			"echo \"1\" > /sys/bus/netdevsim/del_device"
+		]
+	}
 ]