x86: force enable HPET on VT8235/8237 chipsets

This patch adds quirks to force enable HPET on Via VT8235 and
VT8237 chipsets. The datasheet for 8237 documents HPET
functionality (although wrongly) whereas HPET is undocumented
for 8235.

Tested on A7V880 (8237) and K7VT4A+ (8235) boards.

tglx: depends on the force_hept commandline option

Signed-off-by: Udo A. Steinberg <us15@os.inf.tu-dresden.de>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>