Merge branch 'mptcp-pm-userspace-misc-cleanups'

Matthieu Baerts says:

====================
mptcp: pm: userspace: misc cleanups

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

- Patch 1: add a new helper to reduce duplicated code.

- Patch 2: add a macro to iterate over the address list, clearer.

- Patch 3: reduce duplicated code to get the corresponding MPTCP socket.

- Patch 4: move userspace PM specific code out of the in-kernel one.

- Patch 5: pass an entry instead of a list with always one entry.

- Patch 6: uniform struct type used for the local addresses.

- Patch 7: simplify error handling.
====================

Link: https://patch.msgid.link/20241213-net-next-mptcp-pm-misc-cleanup-v1-0-ddb6d00109a8@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>