mptcp: pm: kernel: allow flushing more than 8 endpoints

mptcp: pm: kernel: allow flushing more than 8 endpoints

The mptcp_rm_list structure contains an array of IDs of 8 entries: to be
able to send a RM_ADDR with 8 IDs. This limitation was OK so far because
there could maximum 8 endpoints.

But this is going to change in the next commit. To cope with that, if
one of the arrays is full, the iteration stops, the lists are processed,
then the iteration continues where it previously stopped.

Note that if there are many endpoints to remove, and multiple RM_ADDR to
send, it might be more likely that some of these RM_ADDRs are dropped or
lost. This is a known limitation: RM_ADDR are not retransmitted in
MPTCPv1.

Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260508-net-next-mptcp-pm-inc-limits-v1-3-c84e3fdf9b6a@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>