iscsi: Add parent wwnn/wwpn or fabric capability for createVport

iscsi: Add parent wwnn/wwpn or fabric capability for createVport

https://bugzilla.redhat.com/show_bug.cgi?id=1349696

As it turns out using only the 'parent' to achieve the goal of a
consistent vHBA parent has issues with reboots where the scsi_hostX
parent could change to scsi_hostY causing either failure to create
the vHBA or usage of the wrong HBA for our vHBA.

Thus add the ability to search for the "parent" by the parent wwnn/
wwpn values or just a fabric_name if someone only cares to ensure
usage of the same SAN for the vHBA.