Merge branch 'selftests-assortment-of-fixes'

Petr Machata says:

====================
selftests: Assortment of fixes

This is a loose follow-up to the Kernel CI patchset posted recently. It
contains various fixes that were supposed to be part of said patchset, but
didn't fit due to its size. The latter 4 patches were written independently
of the CI effort, but again didn't fit in their intended patchsets.

- Patch #1 unifies code of two very similar looking functions, busywait()
  and slowwait().

- Patch #2 adds sanity checks around the setting of NETIFS, which carries
  list of interfaces to run on.

- Patch #3 changes bail_on_lldpad() to SKIP instead of FAILing.

- Patches #4 to #7 fix issues in selftests.

- Patches #8 to #10 add topology diagrams to several selftests.
  This should have been part of the mlxsw leg of NH group stats patches,
  but again, it did not fit in due to size.
====================

Link: https://lore.kernel.org/r/cover.1712940759.git.petrm@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>