drm/i915: Drop WaDoubleCursorLP3Latency:ivb

WaDoubleCursorLP3Latency was meant for pre-production hardware.
Drop it.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180130203807.13721-6-ville.syrjala@linux.intel.com


Reviewed-by: Mika Kahola <mika.kahola@intel.com>