drm/i915/bxt: Add WaDisablePooledEuLoadBalancingFix

This is a WA affecting pooled eu which is a bxt specific feature.

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Winiarski, Michal <michal.winiarski@intel.com>
Cc: Zou, Nanhai <nanhai.zou@intel.com>
Cc: Yang, Rong R <rong.r.yang@intel.com>
Cc: Jeff McGee <jeff.mcgee@intel.com>
Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>