Modify VolumeZonePredicate to handle multi-zone PV

Modifies the VolumeZonePredicate to handle a PV that belongs to more
then one zone or region. This is indicated by the zone or region label
value containing a comma separated list.

plugin/pkg/scheduler/algorithm/predicates/predicates.go

@@ -435,7 +435,13 @@ func (c *VolumeZoneChecker) predicate(pod *v1.Pod, meta interface{}, nodeInfo *s
 					continue
 				}
 				nodeV, _ := nodeConstraints[k]
-				if v != nodeV {
+				volumeVSet, err := volumeutil.LabelZonesToSet(v)
+				if err != nil {
+					glog.Warningf("Failed to parse label for %q: %q. Ignoring the label. err=%v. ", k, v, err)
+					continue
+				}
+
+				if !volumeVSet.Has(nodeV) {
 					glog.V(10).Infof("Won't schedule pod %q onto node %q due to volume %q (mismatch on %q)", pod.Name, node.Name, pvName, k)
 					return false, []algorithm.PredicateFailureReason{ErrVolumeZoneConflict}, nil
 				}