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/meson.build b/meson.build
index 8e15733..ffe3d09 100644
--- a/meson.build
+++ b/meson.build
@@ -110,6 +110,7 @@
     'PSSF222201A.json',
     'Rainier 2U Chassis.json',
     'Rainier 4U Chassis.json',
+    'Rainier 1S4U Chassis.json',
     'R1000 Chassis.json',
     'R2000 Chassis.json',
     'SAS Module.json',