x86: force enable HPET on (some?) ICH9 boards

Some consumer ICH9 boards (such as the Abit IP35 Pro) do not provide a BIOS
option for enabling the HPET. The same ICH workaround used for 6,7,8 can be
applied to 9. Here I enable the only PCI id that was visible on my system.

I have confirmed the HPETs work both from userspace and as a clocksource for
the running kernel (2.6.24 here) after applying this patch.

 Force enabled HPET at base address 0xfed00000
 hpet clockevent registered
 hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0, 0
 hpet0: 4 64-bit timers, 14318180 Hz

Signed-off-by: Alistair John Strachan <alistair@devzero.co.uk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>