rtc: add HPET RTC emulation to RTC_DRV_CMOS

That patch adds the RTC emulation of the HPET timer to the new RTC_DRV_CMOS.
The old drivers/char/rtc.ko driver had that functionality and it's important
on new systems.

[akpm@linux-foundation.org: unbreak alpha build]
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Robert Picco <Robert.Picco@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>