Enable BMCWEB_ENABLE_REDFISH_ONE_CHASSIS

Pass the DBMCWEB_ENABLE_REDFISH_ONE_CHASSIS option to bmcweb
for openpower systems. All openpower systems currently only
have a single chassis and no immediate plans to have a
multiple chassis system.

When this build option is set, bmcweb will return a single
redfish chassis named "chassis" which will include all sensors.

This is a short-term solution to solve associating sensors to a
chassis.

Long term, inventory-manager needs to be enhanced to allow sensors
to link to a chassis, or the rest of the project needs to move
to EntityManager.

See https://gerrit.openbmc-project.xyz/#/c/openbmc/bmcweb/+/17563/

Tested: Build an image with this change, loaded on a
        Witherspoon, and see "/redfish/v1/Chassis/chassis"
        and no errors in the Thermal and Power objects.

(From meta-openpower rev: 211da9583b1124dccbf3ab3e701245745affcd22)

Change-Id: I97e78c3ab7d7a755bacbe63af252c033875d880b
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-openpower/recipes-phosphor/bmcweb/bmcweb_%.bbappend b/meta-openpower/recipes-phosphor/bmcweb/bmcweb_%.bbappend
new file mode 100644
index 0000000..ff01b0d
--- /dev/null
+++ b/meta-openpower/recipes-phosphor/bmcweb/bmcweb_%.bbappend
@@ -0,0 +1,6 @@
+SUMMARY = "Modifications to support phosphor-inventory-manager"
+
+# No way to link sensors to a chassis for Redfish in phosphor-inventory-manager.
+# Assume just one chassis via BMCWEB_ENABLE_REDFISH_ONE_CHASSIS option. All
+# IBM systems currently have a single chassis. This is a short-term solution.
+EXTRA_OECMAKE += "-DBMCWEB_ENABLE_REDFISH_ONE_CHASSIS=ON"