iris: Check if resource has stencil before returning it

Signed-off-by: Andrii Kryvytskyi <andrii.o.kryvytskyi@globallogic.com>
Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/gallium/drivers/iris/iris_resource.c

@@ -204,7 +204,11 @@ iris_resource_get_separate_stencil(struct pipe_resource *p_res)
    /* For packed depth-stencil, we treat depth as the primary resource
     * and store S8 as the "second plane" resource.
     */
-   return p_res->next;
+   if (p_res->next && p_res->next->format == PIPE_FORMAT_S8_UINT)
+      return p_res->next;
+
+   return NULL;
+
 }
 
 static void