Merge branch 'mptcp-various-small-improvements'

Matthieu Baerts says:

====================
mptcp: various small improvements

The following patches are not related to each other.

- Patch 1: Avoid sending advertisements on stale subflows, reducing
  risks on loosing them.

- Patch 2: Annotate data-races around subflow->fully_established, using
  READ/WRITE_ONCE().

- Patch 3: A small clean-up on the PM side, avoiding a bit of duplicated
  code.

- Patch 4: Use "Middlebox interference" MP_TCPRST code in reaction to a
  packet received without MPTCP options in the middle of a connection.
====================

Link: https://patch.msgid.link/20241021-net-next-mptcp-misc-6-13-v1-0-1ef02746504a@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>