schemas: Add Decorator.Slot interface

This commit adds `Decorator.Slot` in openbmc-dbus.json with property
`SlotNumber` as described in
https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/yaml\
/xyz/openbmc_project/Inventory/Decorator/Slot.interface.yaml.

This commit also adds `Decorator.Slot` to EMConfig so that the
interface can be configured in Entity Manager configuration file.

Change-Id: I098dc476c224fc7fa77c2969d4d1d31f4d0f7af6
Signed-off-by: Delphine CC Chiu <Delphine_CC_Chiu@wiwynn.com>
diff --git a/schemas/global.json b/schemas/global.json
index 3cbf519..11cd8bf 100644
--- a/schemas/global.json
+++ b/schemas/global.json
@@ -147,6 +147,9 @@
                 "xyz.openbmc_project.Inventory.Decorator.Replaceable": {
                     "$ref": "openbmc-dbus.json#/definitions/xyz/openbmc_project/Inventory/Decorator/Replaceable"
                 },
+                "xyz.openbmc_project.Inventory.Decorator.Slot": {
+                    "$ref": "openbmc-dbus.json#/definitions/xyz/openbmc_project/Inventory/Decorator/Slot"
+                },
                 "xyz.openbmc_project.Inventory.Item.Board.Motherboard": {
                     "$ref": "openbmc-dbus.json#/definitions/xyz/openbmc_project/Inventory/Item/Board/Motherboard"
                 },