timer: move enum definition out of ifdef section

The next patch will setup automatically the broadcast timer for
the different cpuidle driver when one idle state stops its timer.
This will be part of the generic code.

But some ARM boards, like s3c64xx, uses cpuidle but without the
CONFIG_GENERIC_CLOCKEVENTS_BUILD set. Hence the cpuidle framework
will be compiled with the code supposed to be generic, that is
with clockevents_notify and the different enum.

Also the function clockevents_notify is a noop macro, this is fine
except the usual code is:

	int cpu = smp_processor_id();
	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &cpu);

and that raises a warning for the variable cpu which is not used.

Move the clock_event_nofitiers enum definition out of the
CONFIG_GENERIC_CLOCKEVENTS_BUILD section to prevent a compilation
error when these are used in the code.

Change the clockevents_notify macro to a static inline noop function
to prevent a compilation warning.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>