drm/i915: Don't program eLLC IDI hash mask for gen9+

For gen9 onwards, eDRAM is a true memory side cache. So
there is no need to program idi hash mask as it is for eLLC
only.

v2: INTEL_GEN (Chris), s/has/hash (Matthew)
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>

drivers/gpu/drm/i915/i915_gem.c

@@ -4892,7 +4892,7 @@ i915_gem_init_hw(struct drm_device *dev)
 	/* Double layer security blanket, see i915_gem_init() */
 	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
 
-	if (dev_priv->ellc_size)
+	if (dev_priv->ellc_size && INTEL_GEN(dev_priv) < 9)
 		I915_WRITE(HSW_IDICR, I915_READ(HSW_IDICR) | IDIHASHMSK(0xf));
 
 	if (IS_HASWELL(dev))