ibm: Add compatible strings for chassis

Add enums for the compatible strings used by entity-manager for the
various chassis types.

Change-Id: Ibea95513a38359b7c378add391afbb77235a4900
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/yaml/com/ibm/Hardware/Chassis.interface.yaml b/yaml/com/ibm/Hardware/Chassis.interface.yaml
new file mode 100644
index 0000000..f50b1d8
--- /dev/null
+++ b/yaml/com/ibm/Hardware/Chassis.interface.yaml
@@ -0,0 +1,15 @@
+description: >
+    This interface is never intended to be instantiated, but is used to define
+    enumerations for Compatible strings.
+
+enumerations:
+    - name: Model
+      description: >
+          Possible Chassis models used for compatible strings.
+      values:
+          - name: Bonnell
+          - name: Everest
+          - name: Rainier
+          - name: Rainier1S4U
+          - name: Rainier2U
+          - name: Rainier4U