Inventory: Change Item.Chassis interface chassis type to enum

Inventory chassis items can report their chassis type
via management APIs like Redfish.
For this purpose, this commit adds enum values for chassis type.

Signed-off-by: Sharad Yadav <sharady@nvidia.com>
Change-Id: I81fa5d26527126f479051b5735786b08a0210523
diff --git a/yaml/xyz/openbmc_project/Inventory/Item/Chassis.interface.yaml b/yaml/xyz/openbmc_project/Inventory/Item/Chassis.interface.yaml
index df2dc09..e946f80 100644
--- a/yaml/xyz/openbmc_project/Inventory/Item/Chassis.interface.yaml
+++ b/yaml/xyz/openbmc_project/Inventory/Item/Chassis.interface.yaml
@@ -3,6 +3,40 @@
 
 properties:
     - name: Type
-      type: string
+      type: enum[self.ChassisType]
+      default: Unknown
       description: >
           The type of physical form factor of the chassis.
+
+enumerations:
+    - name: ChassisType
+      description: >
+          Possible chassis type
+      values:
+        - name: Component
+          description: >
+              A small chassis, card, or device that contains devices for a
+              particular subsystem or function.
+        - name: Enclosure
+          description: >
+              A generic term for a chassis that does not fit any other
+              description.
+        - name: Module
+          description: >
+              A small, typically removable, chassis or card that contains
+              devices for a particular subsystem or function.
+        - name: RackMount
+          description: >
+              A single-system chassis designed specifically for mounting in an
+              equipment rack.
+        - name: StandAlone
+          description: >
+              A single, free-standing system, commonly called a tower or
+              desktop chassis.
+        - name: Unknown
+          description: >
+              An unknown chassis type.
+        - name: Zone
+          description: >
+              A logical division or portion of a physical chassis that contains
+              multiple devices or systems that cannot be physically separated.