Merge branch 'mptcp-selftests'

Matthieu Baerts says:

====================
selftests: mptcp: cleanups and 'ip mptcp' support

Here are some patches from Geliang, doing different cleanups, and
supporting 'ip mptcp' in more MPTCP selftests.

Patch 1 checks that TC is available in selftests requiring it.

Patch 2 adds 'ms' units in TC commands, to avoid confusions.

Patches 3-9 are some prerequisites for patch 10: some export code from
mptcp_join.sh to mptcp_lib.sh, to be re-used in pm_netlink.sh,
mptcp_sockopt.sh and simult_flows.sh ; and others add helpers to
pm_netlink.sh to easily support both 'ip mptcp' and 'pm_nl_ctl' tools to
interact with the in-kernel MPTCP path-manager.

Patch 10 adds a '-i' parameter in mptcp_sockopt.sh, pm_netlink.sh, and
simult_flows.sh to use 'ip mptcp' tool instead of 'pm_nl_ctl'.

Patch 11 fixes some ShellCheck warnings in pm_netlink.sh, in order to
drop a ShellCheck's 'disable' instruction.
====================

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>