Merge branch 'mptcp-misc-fixes'

Matthieu Baerts says:

====================
mptcp: misc. fixes

Here are two unrelated fixes, plus an extra patch:

- Patch 1: prevent a warning by removing an unneeded and incorrect small
  optimisation in the path-manager. A fix for v5.10.

- Patch 2: reset a subflow when MPTCP opts have been dropped after
  having correctly added a new path. A fix for v5.19.

- Patch 3: add a safety check to prevent issues like the one fixed by
  the second patch.
====================

Link: https://patch.msgid.link/20250224-net-mptcp-misc-fixes-v1-0-f550f636b435@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>