control: Support target_path option in configuration file

The target path containing the interface
xyz.openbmc_project.control.FanPwm or
xyz.openbmc_project.control.FanSpeed can be different between
phosphor-hwmon and dbus-sensor.

In phosphor-hwmon, it is "/xyz/openbmc_project/sensors/fan_tach/".
In dbus-sensor, it is "/xyz/openbmc_project/control/fanpwm/"

This commit supports making this path configurable via "target_path".
By default, it is "/xyz/openbmc_project/sensors/fan_tach/".

Signed-off-by: Chau Ly <chaul@amperecomputing.com>
Change-Id: Id799986ff69455b7c7054070ed2ab3b2e2500a6c
diff --git a/control/fan.cpp b/control/fan.cpp
index d368791..98d4979 100644
--- a/control/fan.cpp
+++ b/control/fan.cpp
@@ -40,7 +40,7 @@
     auto sensors = std::get<sensorListPos>(def);
     for (auto& s : sensors)
     {
-        path = FAN_SENSOR_PATH + s;
+        path = std::get<targetControlPathPos>(def) + s;
         auto service = util::SDBusPlus::getService(bus, path, _interface);
         _sensors[path] = service;
     }