[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/storage/v1beta1/register.go b/vendor/k8s.io/api/storage/v1beta1/register.go
index 06b0f3d..c270ace 100644
--- a/vendor/k8s.io/api/storage/v1beta1/register.go
+++ b/vendor/k8s.io/api/storage/v1beta1/register.go
@@ -49,6 +49,12 @@
 
 		&VolumeAttachment{},
 		&VolumeAttachmentList{},
+
+		&CSIDriver{},
+		&CSIDriverList{},
+
+		&CSINode{},
+		&CSINodeList{},
 	)
 
 	metav1.AddToGroupVersion(scheme, SchemeGroupVersion)