net: sched: Remove unused qdisc_l2t()

This is unused since switch to psched_l2t_ns().

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230615124810.34020-1-yuehaibing@huawei.com


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