team: don't traverse port list using rcu in team_set_mac_address

Currently the list is traversed using rcu variant. That is not correct
since dev_set_mac_address can be called which eventually calls
rtmsg_ifinfo_build_skb and there, skb allocation can sleep. So fix this
by remove the rcu usage here.

Fixes: 3d249d4c "net: introduce ethernet teaming device"
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>