Merge branch 'refactor-duplicate-codes-in-the-qdisc-class-walk-function'

Zhengchao Shao says:

====================
refactor duplicate codes in the qdisc class walk function

The walk implementation of most qdisc class modules is basically the
same. That is, the values of count and skip are checked first. If count
is greater than or equal to skip, the registered fn function is
executed. Otherwise, increase the value of count. So the code can be
refactored.

The walk function is invoked during dump. Therefore, test cases related
 to the tdc filter need to be added.
====================

Link: https://lore.kernel.org/r/20220921024040.385296-1-shaozhengchao@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>