Adding support mtu from interfaces

network/defaults.yaml

@@ -31,6 +31,7 @@ Debian:
       - ipv6ipaddr
       - ipv6netmask
       - ipv6gateway
+      - mtu 
     def_entries:
       - name: lo
         proto: loopback
@@ -92,6 +93,7 @@ RedHat:
       - ipv6ipaddr
       - ipv6netmask
       - ipv6gateway
+      - mtu 
     def_entries: []
 #      - name: lo
 #        proto: none