Hitachi: Port Scheduler for VSP Driver

This bluprint is to add Port Scheduler for the Hitachi VSP Driver.

On Hitachi VSP storage, host groups are created and the same WWNs are
registered in all of the ports that are specified for the parameter
hitachi_compute_target_ports or for the parameter hitachi_target_ports.
For Hitachi storage devices, a maximum of 255 host groups and 255 WWNs
can be registered for one port. When volumes are attached, the upper
limit on the number of WWNs that can be registered might be
unexpectedly exceeded.

For the feature "Port scheduler" by "hitachi_port_scheduler" parameter,
when the cinder-volume service starts, the Fibre Channel Zone Manager obtains
the WWNs of active compute nodes and of active VMs. When volumes are attached,
the WWNs are registered in a round-robin procedure, in the same order as the
order of ports specified for the parameter hitachi_compute_target_ports
or for the parameter hitachi_target_ports.