x86: fix compiler warnings in arch/x86/kernel/early-quirks.c

fix this warning:

arch/x86/kernel/early-quirks.c:40: warning: nvidia_hpet_check defined but not used

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>