Make D-bus systemd error handling consistent

Make consistent with the extra error handling added to the
chassis_state_manager.cpp code

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: I144a692a0472b1db9b45dc14444dd39081c7387a
diff --git a/bmc_state_manager.cpp b/bmc_state_manager.cpp
index 92d9ef8..1ab3f7e 100644
--- a/bmc_state_manager.cpp
+++ b/bmc_state_manager.cpp
@@ -1,8 +1,10 @@
 #include <cassert>
 #include <phosphor-logging/log.hpp>
+#include <phosphor-logging/elog-errors.hpp>
 #include <sdbusplus/exception.hpp>
 #include <sys/sysinfo.h>
 #include "bmc_state_manager.hpp"
+#include "xyz/openbmc_project/Common/error.hpp"
 
 namespace phosphor
 {
@@ -16,6 +18,7 @@
 
 using namespace phosphor::logging;
 using sdbusplus::exception::SdBusError;
+using sdbusplus::xyz::openbmc_project::Common::Error::InternalFailure;
 
 constexpr auto obmcStandbyTarget = "multi-user.target";
 constexpr auto signalDone = "done";
@@ -115,7 +118,9 @@
     }
     catch (const SdBusError& e)
     {
-        log<level::INFO>("Error in Subscribe", entry("ERROR=%s", e.what()));
+        log<level::ERR>("Failed to subscribe to systemd signals",
+                        entry("ERR=%s", e.what()));
+        elog<InternalFailure>();
     }
 
     return;