Add inventory errors

Added NotPresent and Nonfunctional inventory errors.
An example of this being used is to log an error when
a power supply is removed in Witherspoon.
In Witherspoon, both power supplies are needed
to power all 6 GPUs.

Change-Id: I086c2de8e0c44c941c527c44af022c8c440d70f4
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/xyz/openbmc_project/Inventory.errors.yaml b/xyz/openbmc_project/Inventory.errors.yaml
new file mode 100644
index 0000000..45ce7c6
--- /dev/null
+++ b/xyz/openbmc_project/Inventory.errors.yaml
@@ -0,0 +1,4 @@
+- name: NotPresent
+  description: The inventory is not present.
+- name: Nonfunctional
+  description: The inventory is nonfunctional.