v2: Rebased onto Paulo's MHz->kHz change.

v3: Rebased on top of the Haswell pc8+ adjustements.

v4: Use the exact 337.5MHz clock, should have been done as part of v2.
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com> (v1)
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>