[CORD-2270]
Support head node on Ubuntu 16.04 (Xenial)

Change-Id: Ic13ea784b8fa55a481f08d21f5187fd37d13499c
diff --git a/roles/dhcpd/templates/dhcpd.conf.j2 b/roles/dhcpd/templates/dhcpd.conf.j2
index 072d6d7..c54e578 100644
--- a/roles/dhcpd/templates/dhcpd.conf.j2
+++ b/roles/dhcpd/templates/dhcpd.conf.j2
@@ -1,4 +1,3 @@
-
 {#
 Copyright 2017-present Open Networking Foundation
 
@@ -15,7 +14,6 @@
 limitations under the License.
 #}
 
-
 # dhcpd.conf
 # Managed by Ansible!
 
@@ -52,7 +50,7 @@
     option host-name "{{ node.name }}";
 {% set host_ipaddr = (subnet.cidr | ipaddr(node.ipv4_last_octet) | ipaddr('address')) %}
     fixed-address {{ host_ipaddr }};
-    hardware ethernet {{ node.hwaddr | default(hwaddr_prefix ~ (host_ipaddr | ip4_hex)) | hwaddr('unix') }};
+    hardware ethernet {{ node.hwaddr | default(vtn_net_management_host_hwaddr_prefix ~ (host_ipaddr | ip4_hex)) | hwaddr('unix') }};
 {% if node.pxe_filename is defined %}
     filename "{{ node.pxe_filename }}";
     next-server {{ subnet.tftp_server | default(subnet.cidr | ipaddr('1') | ipaddr('address')) }};
@@ -69,7 +67,7 @@
     option host-name "{{ node.name }}";
 {% set host_ipaddr = (subnet.cidr | ipaddr(node.ipv4_last_octet) | ipaddr('address')) %}
     fixed-address {{ host_ipaddr }};
-    hardware ethernet {{ node.hwaddr | default(hwaddr_prefix ~ (host_ipaddr | ip4_hex)) | hwaddr('unix') }};
+    hardware ethernet {{ node.hwaddr | default(vtn_net_management_host_hwaddr_prefix ~ (host_ipaddr | ip4_hex)) | hwaddr('unix') }};
 {% if node.pxe_filename is defined %}
     filename "{{ subnet.pxe_filename }}";
     next-server {{ subnet.tftp_server | default(subnet.cidr | ipaddr('1') | ipaddr('address')) }};