sync: always call BracketValues when recalculating upper/lower brackets

Both ServertimeBracketValues and IdleTimeBracketValues copy the value into
there SysCounter privates. Call it for a NULL set as well, so we don't end up
with stale pointers and we can remove the block/wakeup handlers.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Keith Packard <keithp@keithp.com>

Xext/sync.c

@@ -1058,9 +1058,8 @@ SyncComputeBracketValues(SyncCounter * pCounter)
         }
     }                           /* end for each trigger */
 
-    if (pnewgtval || pnewltval) {
     (*psci->BracketValues) ((pointer) pCounter, pnewltval, pnewgtval);
-    }
+
 }
 
 /*