mptcp: pm: remove '_nl' from mptcp_pm_nl_rm_addr_received

mptcp: pm: remove '_nl' from mptcp_pm_nl_rm_addr_received

Currently, in-kernel PM specific helpers are prefixed with
'mptcp_pm_nl_'. But here 'mptcp_pm_nl_rm_addr_received' is not specific
to this PM: it is called from the PM worker, and used by both the
in-kernel and userspace PMs. The helper has been renamed to
'mptcp_pm_rm_addr_recv' instead of '_received' to avoid confusions with
the one from pm.c.

mptcp_pm_nl_rm_addr_or_subflow', and 'mptcp_pm_nl_rm_subflow_received'
have been updated too for the same reason.

To avoid confusions, the '_nl' bit has been removed from the name.

While at it, the in-kernel PM specific code has been move from
mptcp_pm_rm_addr_or_subflow to a new dedicated helper, clearer.

No behavioural changes intended.

Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250307-net-next-mptcp-pm-reorg-v1-5-abef20ada03b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>