Restore the values in /etc/default/ovirt when kdump config fails

Previously, we restored kdump.conf, but did not restore the proper
entries in /etc/default/ovirt when configuration changes did not
apply cleanly. Do so.

Change-Id: Id9e2c9b9f6969bfbc3ab63a83ae195968dffae40
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=991375
Signed-off-by: Ryan Barry <rbarry@redhat.com>