[PATCH] hpet: fix drift and url

The HPET driver is using a parts per second drift factor instead of the
standard parts per million drift the time interpolator code expects.  This
patch fixes that problem and updates the URL for the HPET spec.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Cc: "Robert W. Picco" <bob.picco@hp.com>
Acked-by: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>