drm/i915: set stc evict disable lra evict w/a

Our workaround list kindly lists that this new default value needs to
be updated in Bspec. Naturally, this did not happen.

Acked-by: Ben Widawsky <ben@bwidawsk.net>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 6d92054..02124a5 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -639,6 +639,7 @@
 #define   CM0_MASK_SHIFT          16
 #define   CM0_IZ_OPT_DISABLE      (1<<6)
 #define   CM0_ZR_OPT_DISABLE      (1<<5)
+#define	  CM0_STC_EVICT_DISABLE_LRA_SNB	(1<<5)
 #define   CM0_DEPTH_EVICT_DISABLE (1<<4)
 #define   CM0_COLOR_EVICT_DISABLE (1<<3)
 #define   CM0_DEPTH_WRITE_DISABLE (1<<1)