Flashsystem need to check I/T map in terminate_connection

[yanjr]

Current code has no check for I/T map and return the data. This might cause zoning lost.
Validation need to be added here for this risk.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/203616

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/203616
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=18578ded46a307a70b030c0dc3f4955273a584a1
Submitter: Jenkins
Branch: master

commit 18578ded46a307a70b030c0dc3f4955273a584a1
Author: Edwin Wang <email address hidden>
Date: Mon Jul 20 20:25:25 2015 +0800

    Add I/T mapping check for IBM FlashSystem

    No initiator_target_map within properties is needed if no more I/T
    connection. Otherwise the FCZone manager will remove the zoning
    between I/T. This patch is to add host check in terminate_connection.
    If no I/T exists, host will be removed in _unmap_vdisk_from_host.

    Closes-Bug: #1469581
    Change-Id: Ide5d2f5cb3557bd167f065fc168722c143f8f267