Merge branch 'mptcp-rx-path-fixes'

Matthieu Baerts says:

====================
mptcp: rx path fixes

Here are 3 different fixes, all related to the MPTCP receive buffer:

- Patch 1: fix receive buffer space when recvmsg() blocks after
  receiving some data. For a fix introduced in v6.12, backported to
  v6.1.

- Patch 2: mptcp_cleanup_rbuf() can be called when no data has been
  copied. For 5.11.

- Patch 3: prevent excessive coalescing on receive, which can affect the
  throughput badly. It looks better to wait a bit before backporting
  this one to stable versions, to get more results. For 5.10.
====================

Link: https://patch.msgid.link/20241230-net-mptcp-rbuf-fixes-v1-0-8608af434ceb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>