selftests: vlan_bridge_binding: Fix flaky operational state check

selftests: vlan_bridge_binding: Fix flaky operational state check

check_operstate() busy waits for up to one second for the operational
state to change to the expected state. This is not enough since carrier
loss events can be delayed by the kernel for up to one second (see
__linkwatch_run_queue()), leading to sporadic failures.

Fix by increasing the busy wait period to two seconds.

Fixes: dca12e9ab760 ("selftests: net: Add a VLAN bridge binding selftest")
Reported-by: Jakub Kicinski <kuba@kernel.org>
Closes: https://lore.kernel.org/netdev/20260616092733.3a31be4d@kernel.org/
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Link: https://patch.msgid.link/20260617104323.1069457-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>