This register exists only pre GEN5, but atm we also access it on
VLV/BXT/CHV. Prevent accessing it on these latter platforms.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>