Fix db settings for keystone with relation to icehouse

The sql section is no longer valid, other options no longer have
 the sql_ predicate.

https://github.com/openstack/keystone/blob/master/keystone/openstack/common/db/options.py

Change-Id: I1a31686bd878f96e1a6a73b8f9812719afd1af9f
Resolves-bug: #1309780
Merge "Fix db settings for keystone with relation to icehouse"