os/wqueue: fix typo
fix typo of comment
*
* Description:
* Queue work to be performed at a later time. All queued work will be
- * performed on the worker thread of of execution (not the caller's).
+ * performed on the worker thread of execution (not the caller's).
*
* The work structure is allocated by caller, but completely managed by
* the work queue logic. The caller should never modify the contents of
