Add ability to configure from dbus

This allows configuration of PID control from dbus using
entity manager. Sample configuration will be pushed to
entity-manager repo shortly.

Tested-by: Used yaml configuration and dbus / entity-manager
           based configuration and pid seemed to work the same.
	   Verified printout of configuration matched generated
	   cpp files.

Change-Id: Ia7b016e53262791ffcccdb9b21c1ccddae2926bc
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/util.cpp b/util.cpp
index 1889256..ca79f35 100644
--- a/util.cpp
+++ b/util.cpp
@@ -22,6 +22,7 @@
 static constexpr auto external_sensor =
     "/xyz/openbmc_project/extsensors/"; // type/
 static constexpr auto openbmc_sensor = "/xyz/openbmc_project/"; // type/
+static constexpr auto dbus_pwm = "/xyz/openbmc_project/control/fanpwm/";
 static constexpr auto sysfs = "/sys/";
 
 
@@ -38,6 +39,11 @@
         return IOInterfaceType::SYSFS;
     }
 
+    if (path.find(dbus_pwm) != std::string::npos)
+    {
+        return IOInterfaceType::DBUSACTIVE;
+    }
+
     return IOInterfaceType::UNKNOWN;
 }