Avoid redundant check for volume create rollback.

The same check will be called during volume delete.
In addition removing createVolumeRollbackError, code 228.

Change-Id: I77e9a1e6c38cbd35f99aecf1422d874fff21449b
Related-to: BZ#960952
Signed-off-by: Eduardo <ewarszaw@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/15764
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>