team: avoid complex list operations in team_nl_cmd_options_set()

The current opt_inst_list operations inside team_nl_cmd_options_set()
is too complex to track:

    LIST_HEAD(opt_inst_list);
    nla_for_each_nested(...) {
        list_for_each_entry(opt_inst, &team->option_inst_list, list) {
            if (__team_option_inst_tmp_find(&opt_inst_list, opt_inst))
                continue;
            list_add(&opt_inst->tmp_list, &opt_inst_list);
        }
    }
    team_nl_send_event_options_get(team, &opt_inst_list);

as while we retrieve 'opt_inst' from team->option_inst_list, it could
be added to the local 'opt_inst_list' for multiple times. The
__team_option_inst_tmp_find() doesn't work, as the setter
team_mode_option_set() still calls team->ops.exit() which uses
->tmp_list too in __team_options_change_check().

Simplify the list operations by moving the 'opt_inst_list' and
team_nl_send_event_options_get() into the nla_for_each_nested() loop so
that it can be guranteed that we won't insert a same list entry for
multiple times. Therefore, __team_option_inst_tmp_find() can be removed
too.

Fixes: 4fb0534f ("team: avoid adding twice the same option to the event list")
Fixes: 2fcdb2c9 ("team: allow to send multiple set events in one message")
Reported-by:  <syzbot+4d4af685432dc0e56c91@syzkaller.appspotmail.com>
Reported-by:  <syzbot+68ee510075cf64260cc4@syzkaller.appspotmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>