Add LED Support to Fan Sensor

This allows the fan sensor to trip an LED when a critical
threshold is crossed.

Tested: Saw LED d-bus object in Group manager get set
using sensor override

Change-Id: Iab5a69ded20de6e3ac99e9ac687c60605d5763d1
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/include/TachSensor.hpp b/include/TachSensor.hpp
index af39d0c..1e5347f 100644
--- a/include/TachSensor.hpp
+++ b/include/TachSensor.hpp
@@ -73,7 +73,8 @@
                std::vector<thresholds::Threshold>&& thresholds,
                const std::string& sensorConfiguration,
                const std::pair<size_t, size_t>& limits,
-               const PowerState& powerState = PowerState::on);
+               const PowerState& powerState,
+               const std::optional<std::string>& led);
     ~TachSensor();
 
   private:
@@ -86,6 +87,8 @@
     boost::asio::deadline_timer waitTimer;
     boost::asio::streambuf readBuf;
     std::string path;
+    std::optional<std::string> led;
+    bool ledState = false;
     size_t errCount;
     void setupRead(void);
     void handleResponse(const boost::system::error_code& err);