Enable Yocto control of the USING_ENTITY_MANAGER_DECORATORS

The USING_ENTITY_MANAGER_DECORATORS compile switch is hard coded to
enabled in a header file. The changes here allow the feature to be
controlled in recipes via PACKAGECONFIG entries in bbappend files.

Tested:
Applied https://gerrit.openbmc.org/c/openbmc/openbmc/+/63434
Modified internal bbappend file to PACKAGECONFIG:remove
entity-manager-decorators
Confirmed the code guarded by the ifdef no longer compiled
Removed change to bbappend file
Confirmed the code guarded by the ifdef was restored.

Change-Id: I4f3072451f893fcb5edaa478d0546253e7005b9f
Signed-off-by: Johnathan Mantey <johnathanx.mantey@intel.com>
diff --git a/dbus-sdr/storagecommands.cpp b/dbus-sdr/storagecommands.cpp
index f123e99..874e5b2 100644
--- a/dbus-sdr/storagecommands.cpp
+++ b/dbus-sdr/storagecommands.cpp
@@ -569,7 +569,7 @@
     return IPMI_CC_OK;
 }
 
-ipmi_ret_t getFruSdrs(ipmi::Context::ptr ctx, size_t index,
+ipmi_ret_t getFruSdrs([[maybe_unused]] ipmi::Context::ptr ctx, size_t index,
                       get_sdr::SensorDataFruRecord& resp)
 {
     if (deviceHashes.size() < index)