x86: preset apic clockevents multiplicator

The check for an unitialized clock event device triggers, when the local
apic timer is registered as a dummy clock event device for broadcasting.
Preset the multiplicator to avoid a false positive.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>