QoS is available in InfiniBox starting with version 4.0.
Older systems will report QoS_support=False.
If QoS is supported and there are QoS specs defined on the
volume type, the driver will apply them on the storage system.
Change-Id: Ic8c702eb95a8e8d5b598508e3072bf825b6f3de1
Implements: blueprint infinidat-qos
