drm/i915: Add Wa_1406306137:icl,ehl

v2:
 - Move to context workarounds.  ROW_CHICKEN4 is part of the context
   image on gen11 (although it isn't on gen12).

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200311162300.1838847-5-matthew.d.roper@intel.com


Reviewed-by: José Roberto de Souza <jose.souza@intel.com>