xfree86: set event->detail for DGA pointer events

Reported-by: Steven Elliott <selliott4@austin.rr.com>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Dave Airlie <airlied@redhat.com>
(cherry picked from commit c5f2818edb)

hw/xfree86/common/xf86DGA.c

@@ -1074,6 +1074,7 @@ DGAProcessPointerEvent(ScreenPtr pScreen, DGAEvent * event, DeviceIntPtr mouse)
     DeviceEvent ev = {
         .header = ET_Internal,
         .length = sizeof(ev),
+        .detail.key = event->detail,
         .type = event->subtype,
         .corestate = butc ? butc->state : 0
     };