Fixed issue with wrong timestamp

Telemetry service used steady_clock for generating timestamps, but it
produced incorrect time. This change makes telemetry service use
steady_clock for intervals and system_clock for timestamps.

Changed readings timestamp to display current timestamp instead of a
time when reading was received.

Tested:
- correct timestamp is visible on dbus
- other telemetry service features are still working

Change-Id: Ic49f45640532cfffaeff5e0bd5591e6d99e5def5
Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
diff --git a/src/numeric_threshold.cpp b/src/numeric_threshold.cpp
index ebb7826..3bec427 100644
--- a/src/numeric_threshold.cpp
+++ b/src/numeric_threshold.cpp
@@ -42,11 +42,11 @@
 }
 
 void NumericThreshold::sensorUpdated(interfaces::Sensor& sensor,
-                                     uint64_t timestamp)
+                                     Milliseconds timestamp)
 {}
 
 void NumericThreshold::sensorUpdated(interfaces::Sensor& sensor,
-                                     uint64_t timestamp, double value)
+                                     Milliseconds timestamp, double value)
 {
     auto& [sensorName, prevValue, dwell, timer] = getDetails(sensor);
     bool decreasing = thresholdValue < prevValue && thresholdValue > value;
@@ -68,8 +68,8 @@
 }
 
 void NumericThreshold::startTimer(const std::string& sensorName,
-                                  uint64_t timestamp, double value, bool& dwell,
-                                  boost::asio::steady_timer& timer)
+                                  Milliseconds timestamp, double value,
+                                  bool& dwell, boost::asio::steady_timer& timer)
 {
     if (dwellTime == Milliseconds::zero())
     {
@@ -93,8 +93,8 @@
     }
 }
 
-void NumericThreshold::commit(const std::string& sensorName, uint64_t timestamp,
-                              double value)
+void NumericThreshold::commit(const std::string& sensorName,
+                              Milliseconds timestamp, double value)
 {
     for (const auto& action : actions)
     {