clockevents: Remove clockevents_notify() prototype

This function no longer exists after commit a49b116d
(clockevents: Cleanup dead cpu explicitely, 2015-04-03). Remove
the prototype and the stub function.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: trivial@kernel.org
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: http://lkml.kernel.org/r/1436984500-5425-1-git-send-email-sboyd@codeaurora.org


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>