HiKey/HiKey960: Fix up new dmabuf_system_heap_device sepolicy fallout am: c090c647c5 am: aaf0e3820b am: 2b915753a0 am: 45c6ff13b2

Original change: https://android-review.googlesource.com/c/device/linaro/hikey/+/1434513

Change-Id: I76fa10006e78b46f1a84bdd31c5a0f7595e5d96b