[VOL-1866] Changed module dependency to v12.0.0 of k8s client-go and v1.15.4 of k8s api/apimachinery in sync with other voltha components

Had to use pseudo-version corresponding to v12.0.0 of k8s client-go
because golang proxy is no longer serving the modules not complying
to Semantic Import Versioning rules including client-go v12.0.0.
Refer to https://github.com/kubernetes/client-go/issues/631 and
https://github.com/golang/go/issues/33558

Change-Id: I2e558bab7f0702f230761319eb5392a7d0532ea3
diff --git a/vendor/k8s.io/api/auditregistration/v1alpha1/types.go b/vendor/k8s.io/api/auditregistration/v1alpha1/types.go
index af31cfe..a0fb48c 100644
--- a/vendor/k8s.io/api/auditregistration/v1alpha1/types.go
+++ b/vendor/k8s.io/api/auditregistration/v1alpha1/types.go
@@ -166,8 +166,6 @@
 	//
 	// If the webhook is running within the cluster, then you should use `service`.
 	//
-	// Port 443 will be used if it is open, otherwise it is an error.
-	//
 	// +optional
 	Service *ServiceReference `json:"service,omitempty" protobuf:"bytes,2,opt,name=service"`
 
@@ -191,4 +189,10 @@
 	// this service.
 	// +optional
 	Path *string `json:"path,omitempty" protobuf:"bytes,3,opt,name=path"`
+
+	// If specified, the port on the service that hosting webhook.
+	// Default to 443 for backward compatibility.
+	// `port` should be a valid port number (1-65535, inclusive).
+	// +optional
+	Port *int32 `json:"port,omitempty" protobuf:"varint,4,opt,name=port"`
 }