Adds storwize_svc_npiv_compatibility_mode flag to Storwize/SVC driver

This configuration option allows the driver to function in an
environment where an attach operation occurs before the virtual FC
ports are logged into the fabric.

Today's behaviour (which is maintained as default behaviour) is to
only build the initiator_target_map for initiator ports that are
logged into the fabric, and error if there are no such ports.

If this new flag is set to True, then if no initiator ports are
found on the fabric, ALL initiator ports are placed into the
initiator_target_map, rather than none, which is the case today.

Closes-Bug: 1346622
Change-Id: Ie722612bc5a9af2816348392c0c39da003b99028
Merge "Adds storwize_svc_npiv_compatibility_mode flag to Storwize/SVC driver"