v2: Keep using the same registers (PCH_*) instead of accidentally
    starting to use the other ones (BXT_*)2) (Jesse)
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>