[PATCH 6.6.y 0/2] mptcp: fix recent failed backports (20250919)

The following patches could not be applied without conflicts in this tree:

- 2293c57484ae ("mptcp: pm: nl: announce deny-join-id0 flag") - 24733e193a0d ("selftests: mptcp: userspace pm: validate deny-join-id0 flag")

Conflicts have been resolved, and documented in each patch.

Matthieu Baerts (NGI0) (2): mptcp: pm: nl: announce deny-join-id0 flag selftests: mptcp: userspace pm: validate deny-join-id0 flag

include/uapi/linux/mptcp.h | 6 ++++-- net/mptcp/pm_netlink.c | 7 +++++++ tools/testing/selftests/net/mptcp/pm_nl_ctl.c | 7 +++++++ tools/testing/selftests/net/mptcp/userspace_pm.sh | 14 +++++++++++--- 4 files changed, 29 insertions(+), 5 deletions(-)