Add back an interface used by an external provider

The move to the new API removed the ipmid_get_sdbus_plus_handler
interface because it looked like it was self-contained in the
executable, not realizing it was needed by an external provider.

Change-Id: I75bb898294cc59cae7d291f7a6a6ed1e61d62903
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
diff --git a/systemintfcmds.cpp b/systemintfcmds.cpp
index 564cc38..4964800 100644
--- a/systemintfcmds.cpp
+++ b/systemintfcmds.cpp
@@ -113,6 +113,12 @@
     __attribute__((init_priority(101)));
 } // namespace
 
+// this is used by openpower-host-ipmi-oem
+std::unique_ptr<sdbusplus::asio::connection>& ipmid_get_sdbus_plus_handler()
+{
+    return sdbusp;
+}
+
 #include <unistd.h>
 void register_netfn_app_functions()
 {