configs: add ibm rainier 1s4u

The rainier 1s4u system will be different enough from the standard 4u
variant that a new config is required. These differences include a
different kernel device tree, different power supplies, and a
different fan configuration.

Tested:
- Verified that when IM keyword was programmed to match the 1s4u that
  correct config was loaded by entity manager
  /xyz/openbmc_project/inventory/system/chassis
     `-/xyz/openbmc_project/inventory/system/chassis/Rainier_1S4U_Chassis
     `-/xyz/openbmc_project/inventory/system/chassis/Rainier_1S4U_Chassis/Compatible_System

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: Ieca50c03154d268726ed9ec541939e73658d427d
diff --git a/schemas/IBM.json b/schemas/IBM.json
index b4fa9b0..84f9cd4 100644
--- a/schemas/IBM.json
+++ b/schemas/IBM.json
@@ -85,6 +85,7 @@
                         "enum": [
                             "ibm,everest",
                             "ibm,rainier-2u",
+                            "ibm,rainier-1s4u",
                             "ibm,rainier-4u",
                             "ibm,rainier"
                         ]