drm/i915: Remove BXT TDL state w/a

This w/a (WaClearTdlStateAckDirtyBits) was only used for preproduction hw,
which is no longer in use. Remove the workaround to simplify the code.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170123130601.2281-5-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/intel_lrc.c

@@ -1170,25 +1170,6 @@ static int gen9_init_perctx_bb(struct intel_engine_cs *engine,
 {
 	uint32_t index = wa_ctx_start(wa_ctx, *offset, CACHELINE_DWORDS);
 
-	/* WaClearTdlStateAckDirtyBits:bxt */
-	if (IS_BXT_REVID(engine->i915, 0, BXT_REVID_B0)) {
-		wa_ctx_emit(batch, index, MI_LOAD_REGISTER_IMM(4));
-
-		wa_ctx_emit_reg(batch, index, GEN8_STATE_ACK);
-		wa_ctx_emit(batch, index, _MASKED_BIT_DISABLE(GEN9_SUBSLICE_TDL_ACK_BITS));
-
-		wa_ctx_emit_reg(batch, index, GEN9_STATE_ACK_SLICE1);
-		wa_ctx_emit(batch, index, _MASKED_BIT_DISABLE(GEN9_SUBSLICE_TDL_ACK_BITS));
-
-		wa_ctx_emit_reg(batch, index, GEN9_STATE_ACK_SLICE2);
-		wa_ctx_emit(batch, index, _MASKED_BIT_DISABLE(GEN9_SUBSLICE_TDL_ACK_BITS));
-
-		wa_ctx_emit_reg(batch, index, GEN7_ROW_CHICKEN2);
-		/* dummy write to CS, mask bits are 0 to ensure the register is not modified */
-		wa_ctx_emit(batch, index, 0x0);
-		wa_ctx_emit(batch, index, MI_NOOP);
-	}
-
 	wa_ctx_emit(batch, index, MI_BATCH_BUFFER_END);
 
 	return wa_ctx_end(wa_ctx, *offset = index, 1);