Monitor : avoid mapper lookups in Tach Sensor

There is a race condition that can fail in certain situations where
mapper has not completed introspection, causing a lookup failure and
D-Bus exception. This change uses a hard-coded service name, thus
avoiding the lookup and allowing tach sensors to write status directly
to inventory.

Signed-off-by: Mike Capps <mikepcapps@gmail.com>
Change-Id: If6ad105055762c6240b36d904d169094088b7c81
diff --git a/monitor/tach_sensor.cpp b/monitor/tach_sensor.cpp
index 13bf1be..029220a 100644
--- a/monitor/tach_sensor.cpp
+++ b/monitor/tach_sensor.cpp
@@ -376,8 +376,11 @@
     auto objectMap =
         util::getObjMap<bool>(_invName, util::OPERATIONAL_STATUS_INTF,
                               util::FUNCTIONAL_PROPERTY, functional);
-    auto response = util::SDBusPlus::lookupAndCallMethod(
-        _bus, util::INVENTORY_PATH, util::INVENTORY_INTF, "Notify", objectMap);
+
+    auto response = util::SDBusPlus::callMethod(
+        _bus, util::INVENTORY_SVC, util::INVENTORY_PATH, util::INVENTORY_INTF,
+        "Notify", objectMap);
+
     if (response.is_method_error())
     {
         log<level::ERR>("Error in notify update of tach sensor inventory");