drm/i915: Implement WaDisableEarlyEOT.

There seems to be another clock gating issue which the workaround is
described as:

   "WA: Set 0xE4F0[1] = 1 to disable Early EOT of thread."

Signed-off-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171216001117.14232-2-rafael.antognolli@intel.com
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index b4807497..9856e24 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1272,6 +1272,9 @@ static int cnl_init_workarounds(struct intel_engine_cs *engine)
 	if (ret)
 		return ret;
 
+	/* WaDisableEarlyEOT:cnl */
+	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, DISABLE_EARLY_EOT);
+
 	return 0;
 }