team: set slave to promisc if team is already in promisc mode

After adding a team interface to bridge, the team interface will enter
promisc mode. Then if we add a new slave to team0, the slave will keep
promisc off. Fix it by setting slave to promisc on if team master is
already in promisc mode, also do the same for allmulti.

v2: add promisc and allmulti checking when delete ports

Fixes: 3d249d4c ("net: introduce ethernet teaming device")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>