Add tach sensors to each fan enclosure

Create a tach sensor instance for each sensor listed within a fan
enclosure that uses 'tach' based presence detection. Each tach sensor
has a pointer to the fan it's associated with and is added to the list
of sensors for that fan enclosure.

Change-Id: I9a83ec52d1a5d01e39702e185336a09edeb4d158
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/fan_enclosure.cpp b/fan_enclosure.cpp
index 346911d..46efeb5 100644
--- a/fan_enclosure.cpp
+++ b/fan_enclosure.cpp
@@ -13,6 +13,12 @@
     //TODO Add this fan to inventory
 }
 
+void FanEnclosure::addSensor(
+    std::unique_ptr<Sensor>&& sensor)
+{
+    FanEnclosure::sensors.push_back(std::move(sensor));
+}
+
 } // namespace presence
 } // namespace fan
 } // namespace phosphor