hpet: /dev/hpet - fixes and cleanup, fix

fix:

On Thursday 31 July 2008, Ingo Molnar wrote:
>   drivers/built-in.o: In function `hpet_alloc':
>   : undefined reference to `__udivdi3'
>   drivers/built-in.o: In function `hpet_alloc':
>   : undefined reference to `__umoddi3'

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>