Merge branch 'mptcp-pm-misc-cleanups-part-2'

Matthieu Baerts says:

====================
mptcp: pm: misc cleanups, part 2

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.

- Patch 1: drop unneeded parameter in a function helper.

- Patch 2: clearer NL error message when an NL attribute is missing.

- Patch 3: more precise NL messages by avoiding 'this or that is NOK'.

- Patch 4: improve too vague or missing NL err messages.

- Patch 5: use GENL_REQ_ATTR_CHECK to look for mandatory NL attributes.

- Patch 6: avoid overriding the error message.

- Patch 7: check all mandatory NL attributes with GENL_REQ_ATTR_CHECK.

- Patch 8: use NL_SET_ERR_MSG_ATTR instead of GENL_SET_ERR_MSG

- Patch 9: move doit callbacks used for both PM to pm.c.

- Patch 10: drop another unneeded parameter in a function helper.

- Patch 11: share the ID parsing code for the 'get_addr' callback.

- Patch 12: share sending NL code for the 'get_addr' callback.

- Patch 13: drop yet another unneeded parameter in a function helper.

- Patch 14: pick the usual structure type for the remote address.

- Patch 15: share the local addr parsing code for the 'set_flags' cb.

The behaviour when there are no errors should then not be modified.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
====================

v2: https://lore.kernel.org/r/20250117-net-next-mptcp-pm-misc-cleanup-2-v2-0-61d4fe0586e8@kernel.org
v1: https://lore.kernel.org/r/20250116-net-next-mptcp-pm-misc-cleanup-2-v1-0-c0b43f18fe06@kernel.org

Link: https://patch.msgid.link/20250207-net-next-mptcp-pm-misc-cleanup-2-v3-0-71753ed957de@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>