3PAR Only remove FC Zone on last volume detach

This patch checks to make sure that we don't
include the initiator_target_map in the return
of terminate_connection if there are volumes
still attached for a particular host.  The
FibreChannel ZoneManager doesn't remove zones
if there isn't an initiator_target_map in the
return of terminate_connection.

Change-Id: I98db5adb6da38454933a6e4b78085193f1d37680
Partial-Bug: #1308318
Merge "3PAR Only remove FC Zone on last volume detach"