sensor-mon: Remove unused variable

Fix clang-tidy error:
```
../sensor-monitor/threshold_alarm_logger.hpp:211:25: error: private field 'event' is not used [-Werror,-Wunused-private-field]
```

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I35ef3a74be5e1db36d39c6ffafbd11e5a784ba87
diff --git a/sensor-monitor/main.cpp b/sensor-monitor/main.cpp
index 1974065..6373b17 100644
--- a/sensor-monitor/main.cpp
+++ b/sensor-monitor/main.cpp
@@ -38,7 +38,7 @@
 
     ShutdownAlarmMonitor shutdownMonitor{bus, event, powerState};
 
-    ThresholdAlarmLogger logger{bus, event, powerState};
+    ThresholdAlarmLogger logger{bus, powerState};
 
     return event.loop();
 }
diff --git a/sensor-monitor/threshold_alarm_logger.cpp b/sensor-monitor/threshold_alarm_logger.cpp
index 54f5a8a..6316dad 100644
--- a/sensor-monitor/threshold_alarm_logger.cpp
+++ b/sensor-monitor/threshold_alarm_logger.cpp
@@ -86,9 +86,8 @@
                               Entry::Level::Informational}}}}}}};
 
 ThresholdAlarmLogger::ThresholdAlarmLogger(
-    sdbusplus::bus_t& bus, sdeventplus::Event& event,
-    std::shared_ptr<PowerState> powerState) :
-    bus(bus), event(event), _powerState(std::move(powerState)),
+    sdbusplus::bus_t& bus, std::shared_ptr<PowerState> powerState) :
+    bus(bus), _powerState(std::move(powerState)),
     warningMatch(bus,
                  "type='signal',member='PropertiesChanged',"
                  "path_namespace='/xyz/openbmc_project/sensors',"
diff --git a/sensor-monitor/threshold_alarm_logger.hpp b/sensor-monitor/threshold_alarm_logger.hpp
index 8b63360..5412208 100644
--- a/sensor-monitor/threshold_alarm_logger.hpp
+++ b/sensor-monitor/threshold_alarm_logger.hpp
@@ -64,10 +64,9 @@
      * Looks for existing active threshold alarms.
      *
      * @param[in] bus - The sdbusplus bus object
-     * @param[in] event - The sdeventplus event object
      * @param[in] powerState - The PowerState object
      */
-    ThresholdAlarmLogger(sdbusplus::bus_t& bus, sdeventplus::Event& event,
+    ThresholdAlarmLogger(sdbusplus::bus_t& bus,
                          std::shared_ptr<phosphor::fan::PowerState> powerState);
 
   private:
@@ -206,11 +205,6 @@
     sdbusplus::bus_t& bus;
 
     /**
-     * @brief The sdeventplus Event object
-     */
-    sdeventplus::Event& event;
-
-    /**
      * @brief The PowerState object to track power state changes.
      */
     std::shared_ptr<phosphor::fan::PowerState> _powerState;