selftests/tc-testing: sfq: check perturb timer values

Add one test to check that the kernel rejects a negative perturb timer.

Add a second test checking that the kernel rejects
a too big perturb timer.

All test results:

1..2
ok 1 cdc1 - Check that a negative perturb timer is rejected
ok 2 a9f0 - Check that a too big perturb timer is rejected

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Link: https://patch.msgid.link/20250613064136.3911944-1-edumazet@google.com


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