VOL-1612: Removed unused docker ARG

Statically set label name given it wont
change.

Change-Id: Ib87dc50e9c7c102b0ce1553ce698968388933fb0
diff --git a/Dockerfile.voltha-onos b/Dockerfile.voltha-onos
index d0017bd..757b01e 100644
--- a/Dockerfile.voltha-onos
+++ b/Dockerfile.voltha-onos
@@ -73,7 +73,6 @@
 RUN touch $ONOS/apps/org.onosproject.openflow-base/active
 
 # Label image
-ARG org_label_schema_name=unknown
 ARG org_label_schema_version=unknown
 ARG org_label_schema_vcs_url=unknown
 ARG org_label_schema_vcs_ref=unknown
@@ -81,7 +80,7 @@
 ARG org_opencord_vcs_commit_date=unknown
 
 LABEL org.label-schema.schema-version=1.0 \
-      org.label-schema.name=$org_label_schema_name \
+      org.label-schema.name=voltha-onos \
       org.label-schema.version=$org_label_schema_version \
       org.label-schema.vcs-url=$org_label_schema_vcs_url \
       org.label-schema.vcs-ref=$org_label_schema_vcs_ref \