phosphor-fan-presence elog error exception.

Implemented elog exception for phosphor fan presence,
replacing runtime_errors.

Change-Id: I70465060838b2cbaeadccf84ed5924e222ac59e3
Signed-off-by: Dinesh Chinari <chinari@us.ibm.com>
diff --git a/monitor/fan.cpp b/monitor/fan.cpp
index 17f5812..195317c 100644
--- a/monitor/fan.cpp
+++ b/monitor/fan.cpp
@@ -199,15 +199,7 @@
     ObjectMap objectMap = getObjectMap(functional);
     std::string service;
 
-    try
-    {
-        service = phosphor::fan::util::getInvService(_bus);
-    }
-    catch (const std::runtime_error& err)
-    {
-        log<level::ERR>(err.what());
-        return;
-    }
+    service = phosphor::fan::util::getInvService(_bus);
 
     auto msg = _bus.new_method_call(service.c_str(),
                                    INVENTORY_PATH,