inventory: add type-only interfaces

Add type-only interfaces for ethernet card, chassis
and system/enclosure.

Change-Id: I347b34790dfc1b0d09c7c6dba9a6950b62d433c0
Signed-off-by: Marri Devender Rao <devenrao@in.ibm.com>
diff --git a/xyz/openbmc_project/Inventory/Item/Chassis.interface.yaml b/xyz/openbmc_project/Inventory/Item/Chassis.interface.yaml
new file mode 100644
index 0000000..6542cc0
--- /dev/null
+++ b/xyz/openbmc_project/Inventory/Item/Chassis.interface.yaml
@@ -0,0 +1,4 @@
+description: >
+    Implement to provide Chassis attributes.
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4