watchdog: Use local_clock for get_timestamp()

The get_timestamp() function is always called with current cpu,
thus using local_clock() would be more appropriate and it makes
the code shorter and cleaner IMHO.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1356576585-28782-1-git-send-email-namhyung@kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>