Merge branch 'mptcp-more-fixes-for-6-3'

Matthieu Baerts says:

====================
mptcp: more fixes for 6.3

Patch 1 avoids scheduling the MPTCP worker on a closed socket on some
edge cases. It fixes issues that can be visible from v5.11.

Patch 2 makes sure the MPTCP worker doesn't try to manipulate
disconnected sockets. This is also a fix for an issue that can be
visible from v5.11.

Patch 3 fixes a NULL pointer dereference when MPTCP FastOpen is used
and an early fallback is done. A fix for v6.2.

Patch 4 improves the stability of the userspace PM selftest for a
subtest added in v6.2.
====================

Link: https://lore.kernel.org/r/20230411-upstream-net-20230411-mptcp-fixes-v1-0-ca540f3ef986@tessares.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>