For an IB port, a slave should not show port active until that slave
has a valid alias-guid (provided by the subnet manager).  Therefore
the port-up event should be passed to a slave only after both the port
is up, and the slave's alias-guid has been set.

Also, provide the infrastructure for propagating port-management
events (client-reregister, etc) to slaves.
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <roland@purestorage.com>