Merge branch 'mptcp-selftest-fine-tuning-and-cleanup'

Mat Martineau says:

====================
mptcp: Selftest fine-tuning and cleanup

Patch 1 adjusts the mptcp selftest timeout to account for slow machines
running debug builds.

Patch 2 simplifies one test function.

Patches 3-6 do some cleanup, like deleting unused variables and avoiding
extra work when only printing usage information.

Patch 7 improves the checksum tests by utilizing existing checksum MIBs.
====================

Link: https://lore.kernel.org/r/20220218030311.367536-1-mathew.j.martineau@linux.intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>