call: prevent display sleep during call

Change-Id: If3af66d9e4519ca66f8fa844396afd5c429d0ce6
diff --git a/src/CurrentCallVC.mm b/src/CurrentCallVC.mm
index 7a985c8..913aa83 100644
--- a/src/CurrentCallVC.mm
+++ b/src/CurrentCallVC.mm
@@ -559,6 +559,8 @@
             [self.delegate callFinished];
             [self removeConferenceLayout];
             [self switchToNextConferenceCall: confUid_];
+            AppDelegate* appDelegate = (AppDelegate *)[[NSApplication sharedApplication] delegate];
+            [appDelegate restoreScreenSleep];
             break;
     }
 }