Revert "No $end in this function, and it appears to be optional, so r…

…emove the non-existent variable"

This reverts commit 596c52a.

turba/lib/Api.php

@@ -2273,7 +2273,7 @@ protected function _getSources($sources, $synchronize = false)
                 $driver = $GLOBALS['injector']
                     ->getInstance('Turba_Factory_Driver')
                     ->create($val)
-                    ->synchronize();
+                    ->synchronize($end);
             }
         }