team: use operstate consistently for linkup

When a port is added to a team, its initial state is derived
from netif_carrier_ok rather than netif_oper_up.
If it is carrier up but operationally down at the time of being
added, the port state.linkup will be set prematurely.
port state.linkup should be set consistently using
netif_oper_up rather than netif_carrier_ok.

Fixes: f1d22a1e ("team: account for oper state")
Signed-off-by: George Wilkie <gwilkie@vyatta.att-mail.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>