[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/scheduling/v1/register.go b/vendor/k8s.io/api/scheduling/v1/register.go
new file mode 100644
index 0000000..33977fe
--- /dev/null
+++ b/vendor/k8s.io/api/scheduling/v1/register.go
@@ -0,0 +1,55 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1
+
+import (
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+// GroupName is the group name use in this package
+const GroupName = "scheduling.k8s.io"
+
+// SchemeGroupVersion is group version used to register these objects
+var SchemeGroupVersion = schema.GroupVersion{Group: GroupName, Version: "v1"}
+
+// Resource takes an unqualified resource and returns a Group qualified GroupResource
+func Resource(resource string) schema.GroupResource {
+	return SchemeGroupVersion.WithResource(resource).GroupResource()
+}
+
+var (
+	// TODO: move SchemeBuilder with zz_generated.deepcopy.go to k8s.io/api.
+	// localSchemeBuilder and AddToScheme will stay in k8s.io/kubernetes.
+
+	// SchemeBuilder is a collection of functions that add things to a scheme.
+	SchemeBuilder      = runtime.NewSchemeBuilder(addKnownTypes)
+	localSchemeBuilder = &SchemeBuilder
+	// AddToScheme applies all the stored functions to the scheme.
+	AddToScheme = localSchemeBuilder.AddToScheme
+)
+
+// Adds the list of known types to the given scheme.
+func addKnownTypes(scheme *runtime.Scheme) error {
+	scheme.AddKnownTypes(SchemeGroupVersion,
+		&PriorityClass{},
+		&PriorityClassList{},
+	)
+	metav1.AddToGroupVersion(scheme, SchemeGroupVersion)
+	return nil
+}