mi: Build fix: mieqProcessDeviceEvent returns void

mieq.c:520:9: error: void function 'mieqProcessDeviceEvent' should not return a value [-Wreturn-type,Semantic Issue]
        return 0;
        ^      ~
1 error generated.

Regression-from: 9fb08310b5
Found-by: Tinderbox

Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>

mi/mieq.c

@@ -517,7 +517,7 @@ mieqProcessDeviceEvent(DeviceIntPtr dev, InternalEvent *event, ScreenPtr screen)
 
     /* refuse events from disabled devices */
     if (!dev->enabled)
-        return 0;
+        return;
 
     /* Custom event handler */
     handler = miEventQueue.handlers[event->any.type];