drm/i915: Free wa_batchbuffer when freeing error state

wa_batchbuffer is part of some error states. Make sure it
is freed.

Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -554,6 +554,7 @@ static void i915_error_state_free(struct kref *error_ref)
 
 	for (i = 0; i < ARRAY_SIZE(error->ring); i++) {
 		i915_error_object_free(error->ring[i].batchbuffer);
+		i915_error_object_free(error->ring[i].wa_batchbuffer);
 		i915_error_object_free(error->ring[i].ringbuffer);
 		i915_error_object_free(error->ring[i].hws_page);
 		i915_error_object_free(error->ring[i].ctx);