drm/i915: Drop VLV checks from rc6p and rc6pp sysfs files

We don't register the rc6p and rc6pp sysfs files on VLV, so there's no
point in having any VLV checks in them. Drop the checks.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Deepak S<deepak.s@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>