timers: Fix parameter description of try_to_del_timer_sync()

Signed-off-by: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Link: http://lkml.kernel.org/r/20170530194103.7454-1-pmeerw@pmeerw.net


Cc: John Stultz <john.stultz@linaro.org>
Cc: trivial@rustcorp.com.au
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>