Merge branch 'mptcp-pm-misc-cleanups-part-3'

Matthieu Baerts says:

====================
mptcp: pm: misc cleanups, part 3

These cleanups lead the way to the unification of the path-manager
interfaces, and allow future extensions. The following patches are not
all linked to each others, but are all related to the path-managers,
except the last three.

- Patch 1: remove unused returned value in mptcp_nl_set_flags().
- Patch 2: new flag: avoid iterating over all connections if not needed.
- Patch 3: add a build check making sure there is enough space in cb-ctx.
- Patch 4: new mptcp_pm_genl_fill_addr helper to reduce duplicated code.
- Patch 5: simplify userspace_pm_append_new_local_addr helper.
- Patch 6: drop unneeded inet6_sk().
- Patch 7: use ipv6_addr_equal() instead of !ipv6_addr_cmp()
- Patch 8: scheduler: split an interface in two.
- Patch 9: scheduler: save 64 bytes of currently unused data.
- Patch 10: small optimisation to exit early in case of retransmissions.
====================

Link: https://patch.msgid.link/20250221-net-next-mptcp-pm-misc-cleanup-3-v1-0-2b70ab1cee79@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>