Delete description of the disk
Delete description of the disk

Now,flavor-list can return disk property.So I think can delete this
description of disk

Change-Id: Ia0f9c5ec38ce6dc5171adee857b2e4078685cb7c

zhangg/trove,zhangg/trove,hplustree/trove,openstack/trove,hplustree/trove,openstack/trove