Updated openstack/openstack
Project: openstack/nova  6f3748af5e96b322fc14363698a43f21a43c7b24

Remove outdated docstring for XenApi driver's options

XenAPI's driver options's help strings can explain how to
use these options, so remove these duplicated and outdated
docstring.

Change-Id: I3de257e75ba13352e9460070f5bb2a6d7cf36a4e