[rgmanager] Make rgmanager check pbond links correctly
    
    Rgmanager doesn't check pbond links (bonded links when Xen
    networking is used) correctly.  This patch fixes it.
    
    Red Hat Bugzilla #451654
    
    Patch from John Ruemker.
    
    Signed-off-by: John Ruemker <jruemker@redhat.com>
    Signed-off-by: Lon Hohberger <lhh@redhat.com>