mptcp: pm: in-kernel: reduce parameters of set_flags

mptcp: pm: in-kernel: reduce parameters of set_flags

The number of parameters in mptcp_nl_set_flags() can be reduced.
Only need to pass a "local" parameter to it instead of "local->addr"
and "local->flags".

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250228-net-next-mptcp-coverage-small-opti-v1-4-f933c4275676@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>