Modify mako script to generate code for empty interfaces

Empty interfaces are added for inventory objects to determine
the type of the object

Change-Id: I4b08e50a2ee45a3156012c0ef6b3ff53bd06c644
Signed-off-by: Marri Devender Rao <devenrao@in.ibm.com>
diff --git a/writefru.yaml b/writefru.yaml
index eb7f827..1673225 100644
--- a/writefru.yaml
+++ b/writefru.yaml
@@ -7,9 +7,10 @@
         VINI,DR: PrettyName
     xyz.openbmc_project.Common.UUID:
         OPFR,UD: UUID
-
+    xyz.openbmc_project.Inventory.Item.Bmc:
 
 ETHERNET:
     xyz.openbmc_project.Inventory.Item.NetworkInterface:
         VINI,B1: MACAddress
         OPFR,B1: MACAddress
+    xyz.openbmc_project.Inventory.Item.Ethernet: