power-button: fix released signal to include duration

The latest dbus interface requires a duration in microseconds for
the PowerButton.Released signal.  Add it in now so that the code
successfully compiles.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib82db55b9c7e50cc018f5e3a5b1f0c71b9d4c7c7
diff --git a/src/power_button.cpp b/src/power_button.cpp
index b6a89b9..195030a 100644
--- a/src/power_button.cpp
+++ b/src/power_button.cpp
@@ -87,7 +87,8 @@
         else
         {
             // released
-            released();
+            released(std::chrono::duration_cast<std::chrono::microseconds>(d)
+                         .count());
         }
     }
 }