Allow getFileStats for non NFS ISO domains

getFileStats only allowed file stats to be gathered from NFS ISO domains.
We currently support ISO domains on any file storage domain so the check
was corrected.

Change-Id: I7107d20b1b8b341086800bb35def895a70c4b4f0
Signed-off-by: Tal Nisan <tnisan@redhat.com>
Bug-Url: https://bugzilla.redhat.com/1075172
Reviewed-on: http://gerrit.ovirt.org/25627
Reviewed-by: Allon Mureinik <amureini@redhat.com>
Reviewed-by: Federico Simoncelli <fsimonce@redhat.com>