Input: tps6507x-ts - a couple work queue cleanups

1) Use msecs_to_jiffies() instead of calculating by hand.
2) Call cancel_delayed_work_sync() instead of cancel_delayed_work()
   followed by a separate flush_workqueue().
3) Remove the "tsc->wq = 0;"  Sparse complains about that because
   tsc->wq is a pointer, not an int.  It's not needed because we just
   free the pointer anyway.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>