mISDN: misc timerdev fixes

- Remove noop VFS stubs. The VFS does that on a NULL pointer anyways.
- Fix timer handler prototype to be correct
- Comment ugly SMP race I didn't fix.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>