team: allow to enable/disable ports

This patch changes content of hashlist (used to get port struct by
computed index (0...en_port_count-1)). Now the hash list contains only
enabled ports so userspace will be able to say what ports can be used
for tx/rx. This becomes handy when userspace will need to disable ports
which does not belong to active aggregator. By default, newly added port
is enabled.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>