State.BMC: add event for RebootCause

When the BMC comes out of reset, some chips provide a reason / cause
of the last reboot.  This is already saved in the BMC interface.
Define an event which can also be used to record this.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I8fde0e341261a5d7a20af3c1a9f672dfe3b103a9
diff --git a/yaml/xyz/openbmc_project/State/BMC.events.yaml b/yaml/xyz/openbmc_project/State/BMC.events.yaml
new file mode 100644
index 0000000..016a49c
--- /dev/null
+++ b/yaml/xyz/openbmc_project/State/BMC.events.yaml
@@ -0,0 +1,12 @@
+version: 1.0.0
+
+events:
+    - name: RebootCause
+      metadata:
+          - name: Cause
+            type: enum[xyz.openbmc_project.State.BMC.RebootCause]
+            primary: true
+            description: The detected cause of the last BMC reboot.
+      en:
+          description: The BMC reboot and the cause was identified.
+          message: The last BMC reboot was caused by '{Cause}'.